contains 177 rules |
System Settingsgroup |
contains 143 rules |
Installing and Maintaining SoftwaregroupThe following sections contain information on
security-relevant choices during the initial operating system
installation process and the setup of software
updates. |
contains 14 rules |
Disk PartitioninggroupTo ensure separation and protection of data, there
are top-level system directories which should be placed on their
own physical partition or logical volume. The installer's default
partitioning scheme creates separate logical volumes for
/, /boot, and swap.
If starting with any of the default layouts, check the box to
"Review and modify partitioning." This allows for the easy creation
of additional logical volumes inside the volume group already
created, though it may require making /'s logical volume smaller to
create space. In general, using logical volumes is preferable to
using partitions because they can be more easily adjusted
later.If creating a custom layout, create the partitions mentioned in
the previous paragraph (which the installer will require anyway),
as well as separate ones described in the following sections.
If a system has already been installed, and the default
partitioning scheme was used, it is possible but nontrivial to
modify it to create separate logical volumes for the directories
listed above. The Logical Volume Manager (LVM) makes this possible.
See the LVM HOWTO at http://tldp.org/HOWTO/LVM-HOWTO/ for more
detailed information on LVM. |
contains 5 rules |
Ensure /tmp Located On Separate Partitionrule
The /tmp directory is a world-writable directory used
for temporary file storage. Ensure it has its own partition or
logical volume at installation time, or migrate it using LVM.
identifiers:
CCE-26435-8, DISA FSO RHEL-06-000001 references:
SC-32, 1208, Test attestation on 20120928 by MM |
Ensure /var Located On Separate PartitionruleThe /var directory is used by daemons and other system
services to store frequently-changing data. Ensure that /var has its own partition
or logical volume at installation time, or migrate it using LVM.
identifiers:
CCE-26639-5, DISA FSO RHEL-06-000002 references:
SC-32, 1208, Test attestation on 20120928 by MM |
Ensure /var/log Located On Separate Partitionrule
System logs are stored in the /var/log directory.
Ensure that it has its own partition or logical
volume at installation time, or migrate it using LVM.
identifiers:
CCE-26215-4, DISA FSO RHEL-06-000003 references:
AU-9, SC-32, 1208, Test attestation on 20120928 by MM |
Ensure /var/log/audit Located On Separate Partitionrule
Audit logs are stored in the /var/log/audit directory. Ensure that it
has its own partition or logical volume at installation time, or migrate it
later using LVM. Make absolutely certain that it is large enough to store all
audit logs that will be created by the auditing daemon.
identifiers:
CCE-26436-6, DISA FSO RHEL-06-000004 references:
AU-4, AU-9, SC-32, 137, 138, 1208, Test attestation on 20120928 by MM |
Ensure /home Located On Separate Partitionrule
If user home directories will be stored locally, create a separate partition
for /home at installation time (or migrate it later using LVM). If
/home will be mounted from another system such as an NFS server, then
creating a separate partition is not necessary at installation time, and the
mountpoint can instead be configured later.
identifiers:
CCE-26557-9, DISA FSO RHEL-06-000007 references:
SC-32, 1208, Test attestation on 20120928 by MM |
Updating SoftwaregroupThe yum command line tool is used to install and
update software packages. The system also provides a graphical
software update tool in the System menu, in the Administration submenu,
called Software Update.
Red Hat Enterprise Linux systems contain an installed software catalog called
the RPM database, which records metadata of installed packages. Consistently using
yum or the graphical Software Update for all software installation
allows for insight into the current inventory of installed software on the system.
|
contains 3 rules |
Ensure Red Hat GPG Key Installedrule
To ensure the system can cryptographically verify base software
packages come from Red Hat (and to connect to the Red Hat Network to
receive them), the Red Hat GPG key must properly be installed.
To install the Red Hat GPG key, run:
$ sudo rhn_register
If the system is not connected to the Internet or an RHN Satellite,
then install the Red Hat GPG key from trusted media such as
the Red Hat installation CD-ROM or DVD. Assuming the disc is mounted
in /media/cdrom, use the following command as the root user to import
it into the keyring:
$ sudo rpm --import /media/cdrom/RPM-GPG-KEY
identifiers:
CCE-26506-6, DISA FSO RHEL-06-000008 references:
SI-7, MA-1(b), 351, Test attestation on 20120928 by MM Remediation script:# The two fingerprints below are retrieved from https://access.redhat.com/security/team/key
readonly REDHAT_RELEASE_2_FINGERPRINT="567E 347A D004 4ADE 55BA 8A5F 199E 2F91 FD43 1D51"
readonly REDHAT_AUXILIARY_FINGERPRINT="43A6 E49C 4A38 F4BE 9ABF 2A53 4568 9C88 2FA6 58E0"
# Location of the key we would like to import (once it's integrity verified)
readonly REDHAT_RELEASE_KEY="/etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release"
RPM_GPG_DIR_PERMS=$(stat -c %a "$(dirname "$REDHAT_RELEASE_KEY")")
# Verify /etc/pki/rpm-gpg directory permissions are safe
if [ "${RPM_GPG_DIR_PERMS}" -le "755" ]
then
# If they are safe, try to obtain fingerprints from the key file
# (to ensure there won't be e.g. CRC error)
IFS=$'\n' GPG_OUT=($(gpg --with-fingerprint "${REDHAT_RELEASE_KEY}"))
GPG_RESULT=$?
# No CRC error, safe to proceed
if [ "${GPG_RESULT}" -eq "0" ]
then
for ITEM in "${GPG_OUT[@]}"
do
# Filter just hexadecimal fingerprints from gpg's output from
# processing of a key file
RESULT=$(echo ${ITEM} | sed -n "s/[[:space:]]*Key fingerprint = \(.*\)/\1/p" | tr -s '[:space:]')
# If fingerprint matches Red Hat's release 2 or auxiliary key import the key
if [[ ${RESULT} ]] && ([[ ${RESULT} = "${REDHAT_RELEASE_2_FINGERPRINT}" ]] || \
[[ ${RESULT} = "${REDHAT_AUXILIARY_FINGERPRINT}" ]])
then
rpm --import "${REDHAT_RELEASE_KEY}"
fi
done
fi
fi
|
Ensure gpgcheck Enabled In Main Yum ConfigurationruleThe gpgcheck option controls whether
RPM packages' signatures are always checked prior to installation.
To configure yum to check package signatures before installing
them, ensure the following line appears in /etc/yum.conf in
the [main] section:
gpgcheck=1
identifiers:
CCE-26709-6, DISA FSO RHEL-06-000013 references:
SI-7, MA-1(b), 352, 663, Test attestation on 20120928 by MM |
Ensure gpgcheck Enabled For All Yum Package RepositoriesruleTo ensure signature checking is not disabled for
any repos, remove any lines from files in /etc/yum.repos.d of the form:
gpgcheck=0
identifiers:
CCE-26647-8, DISA FSO RHEL-06-000015 references:
SI-7, MA-1(b), 352, 663, Test attestation on 20120928 by MM |
Software Integrity Checkinggroup
Both the AIDE (Advanced Intrusion Detection Environment)
software and the RPM package management system provide
mechanisms for verifying the integrity of installed software.
AIDE uses snapshots of file metadata (such as hashes) and compares these
to current system files in order to detect changes.
The RPM package management system can conduct integrity
checks by comparing information in its metadata database with
files installed on the system.
Integrity checking cannot prevent intrusions,
but can detect that they have occurred. Requirements
for software integrity checking may be highly dependent on
the environment in which the system will be used. Snapshot-based
approaches such as AIDE may induce considerable overhead
in the presence of frequent software updates.
|
contains 6 rules |
Verify Integrity with AIDEgroupAIDE conducts integrity checks by comparing information about
files with previously-gathered information. Ideally, the AIDE database is
created immediately after initial system configuration, and then again after any
software update. AIDE is highly configurable, with further configuration
information located in /usr/share/doc/aide-VERSION.
|
contains 4 rules |
Install AIDErule
Install the AIDE package with the command:
$ sudo yum install aide
identifiers:
CCE-27024-9, DISA FSO RHEL-06-000016 references:
CM-3(d), CM-3(e), CM-6(d), SC-28, SI-7, 1069, Test attestation on 20121024 by DS Remediation script:yum -y install aide
|
Disable Prelinkingrule
The prelinking feature changes binaries in an attempt to decrease their startup
time. In order to disable it, change or add the following line inside the file
/etc/sysconfig/prelink:
PRELINKING=no
Next, run the following command to return binaries to a normal, non-prelinked state:
$ sudo /usr/sbin/prelink -ua
identifiers:
CCE-27221-1 references:
CM-6(d), SC-28, SI-7 Remediation script:#
# Disable prelinking altogether
#
if grep -q ^PRELINKING /etc/sysconfig/prelink
then
sed -i 's/PRELINKING.*/PRELINKING=no/g' /etc/sysconfig/prelink
else
echo -e "\n# Set PRELINKING=no per security requirements" >> /etc/sysconfig/prelink
echo "PRELINKING=no" >> /etc/sysconfig/prelink
fi
#
# Undo previous prelink changes to binaries
#
/usr/sbin/prelink -ua
|
Build and Test AIDE DatabaseruleRun the following command to generate a new database:
$ sudo /usr/sbin/aide --init
By default, the database will be written to the file /var/lib/aide/aide.db.new.gz.
Storing the database, the configuration file /etc/aide.conf, and the binary
/usr/sbin/aide (or hashes of these files), in a secure location (such as on read-only media) provides additional assurance about their integrity.
The newly-generated database can be installed as follows:
$ sudo cp /var/lib/aide/aide.db.new.gz /var/lib/aide/aide.db.gz
To initiate a manual check, run the following command:
$ sudo /usr/sbin/aide --check
If this check produces any unexpected output, investigate.
identifiers:
CCE-27135-3, DISA FSO RHEL-06-000018 references:
CM-3(d), CM-3(e), CM-6(d), SC-28, SI-7, 374, 416, 1069, 1263, 1297, 1589 |
Configure Periodic Execution of AIDErule
To implement a daily execution of AIDE at 4:05am using cron, add the following line to /etc/crontab:
05 4 * * * root /usr/sbin/aide --check
AIDE can be executed periodically through other means; this is merely one example.
identifiers:
CCE-27222-9, DISA FSO RHEL-06-000306 references:
CM-3(d), CM-3(e), CM-6(d), SC-28, SI-7, 374, 416, 1069, 1263, 1297, 1589 Remediation script:echo "05 4 * * * root /usr/sbin/aide --check" >> /etc/crontab
|
Verify Integrity with RPMgroupThe RPM package management system includes the ability
to verify the integrity of installed packages by comparing the
installed files with information about the files taken from the
package metadata stored in the RPM database. Although an attacker
could corrupt the RPM database (analogous to attacking the AIDE
database as described above), this check can still reveal
modification of important files. To list which files on the system differ from what is expected by the RPM database:
$ rpm -qVa
See the man page for rpm to see a complete explanation of each column.
|
contains 2 rules |
Verify and Correct File Permissions with RPMrule
The RPM package management system can check file access
permissions of installed software packages, including many that are
important to system security.
After locating a file with incorrect permissions, run the following command to determine which package owns it:
$ rpm -qf FILENAME
Next, run the following command to reset its permissions to
the correct values:
$ sudo rpm --setperms PACKAGENAME
identifiers:
CCE-26731-0, DISA FSO RHEL-06-000518 references:
AC-6, CM-6(d), SI-7, 1493, 1494, 1495 |
Verify File Hashes with RPMruleThe RPM package management system can check the hashes of
installed software packages, including many that are important to system
security. Run the following command to list which files on the system
have hashes that differ from what is expected by the RPM database:
$ rpm -Va | grep '^..5'
A "c" in the second column indicates that a file is a configuration file, which
may appropriately be expected to change. If the file was not expected to
change, investigate the cause of the change using audit logs or other means.
The package can then be reinstalled to restore the file.
Run the following command to determine which package owns the file:
$ rpm -qf FILENAME
The package can be reinstalled from a yum repository using the command:
$ sudo yum reinstall PACKAGENAME
Alternatively, the package can be reinstalled from trusted media using the command:
$ sudo rpm -Uvh PACKAGENAME
identifiers:
CCE-27223-7, DISA FSO RHEL-06-000519 references:
CM-6(d), SI-7, 1496 |
File Permissions and MasksgroupTraditional Unix security relies heavily on file and
directory permissions to prevent unauthorized users from reading or
modifying files to which they should not have access.
Several of the commands in this section search filesystems
for files or directories with certain characteristics, and are
intended to be run on every local partition on a given system.
When the variable PART appears in one of the commands below,
it means that the command is intended to be run repeatedly, with the
name of each local partition substituted for PART in turn.
The following command prints a list of all ext4 partitions on the local
system, which is the default filesystem for Red Hat Enterprise Linux
6 installations:
$ mount -t ext4 | awk '{print $3}'
For any systems that use a different
local filesystem type, modify this command as appropriate.
|
contains 42 rules |
Restrict Partition Mount OptionsgroupSystem partitions can be mounted with certain options
that limit what files on those partitions can do. These options
are set in the /etc/fstab configuration file, and can be
used to make certain types of malicious behavior more difficult. |
contains 11 rules |
Add nodev Option to Non-Root Local PartitionsruleThe nodev mount option prevents files from being
interpreted as character or block devices.
Legitimate character and block devices should exist only in
the /dev directory on the root partition or within chroot
jails built for system services.
Add the nodev option to the fourth column of
/etc/fstab for the line which controls mounting of
any non-root local partitions.
identifiers:
CCE-27045-4 references:
CM-7 Remediation script:
# NOTE: Run-time reconfiguration of partitions' mount options is not possible.
# After performing this remediation be sure to also subsequently reboot the
# system as soon as possible for the remediation to take the effect!
# Shortened ID for frequently used character class
SP="[:space:]"
# Load /etc/fstab's content with LABEL= and UUID= tags expanded to real
# device names into FSTAB_REAL_DEVICES array splitting items by newline
IFS=$'\n' FSTAB_REAL_DEVICES=($(findmnt --fstab --evaluate --noheadings))
for line in ${FSTAB_REAL_DEVICES[@]}
do
# For each line:
# * squeeze multiple space characters into one,
# * split line content info four columns (target, source, fstype, and
# mount options) by space delimiter
IFS=$' ' read TARGET SOURCE FSTYPE MOUNT_OPTIONS <<< "$(echo $line | tr -s ' ')"
# Filter the targets according to the following criteria:
# * don't include record for root partition,
# * include the target only if it has the form of '/word.*' (not to include
# special entries like e.g swap),
# * include the target only if its source has the form of '/dev.*'
# (to process only local partitions)
if [[ ! $TARGET =~ ^\/$ ]] && # Don't include root partition
[[ $TARGET =~ ^\/[A-Za-z0-9_] ]] && # Include if target =~ '/word.*'
[[ $SOURCE =~ ^\/dev ]] # Include if source =~ '/dev.*'
then
# Check the mount options column if it doesn't contain 'nodev' keyword yet
if ! grep -q "nodev" <<< "$MOUNT_OPTIONS"
then
# Check if current mount options is empty string ('') meaning
# particular /etc/fstab row contain just 'defaults' keyword
if [[ ${#MOUNT_OPTIONS} == "0" ]]
then
# If so, add 'defaults' back and append 'nodev' keyword
MOUNT_OPTIONS="defaults,nodev"
else
# Otherwise append just 'nodev' keyword
MOUNT_OPTIONS="$MOUNT_OPTIONS,nodev"
fi
# Escape possible slash ('/') characters in target for use as sed
# expression below
TARGET_ESCAPED=${TARGET//$'/'/$'\/'}
# This target doesn't contain 'nodev' in mount options yet (and meets
# the above filtering criteria). Therefore obtain particular /etc/fstab's
# row into FSTAB_TARGET_ROW variable separating the mount options field with
# hash '#' character
FSTAB_TARGET_ROW=$(sed -n "s/\(.*$TARGET_ESCAPED[$SP]\+$FSTYPE[$SP]\+\)\([^$SP]\+\)/\1#\2#/p" /etc/fstab)
# Split the retrieved value by the hash '#' delimiter to get the
# row's head & tail (i.e. columns other than mount options) which won't
# get modified
IFS=$'#' read TARGET_HEAD TARGET_OPTS TARGET_TAIL <<< "$FSTAB_TARGET_ROW"
# Replace old mount options for particular /etc/fstab's row (for this target
# and fstype) with new mount options
sed -i "s#${TARGET_HEAD}\(.*\)${TARGET_TAIL}#${TARGET_HEAD}${MOUNT_OPTIONS}${TARGET_TAIL}#" /etc/fstab
fi
fi
done
|
Add nodev Option to Removable Media PartitionsruleThe nodev mount option prevents files from being
interpreted as character or block devices.
Legitimate character and block devices should exist only in
the /dev directory on the root partition or within chroot
jails built for system services.
Add the nodev option to the fourth column of
/etc/fstab for the line which controls mounting of
any removable media partitions.
identifiers:
CCE-26860-7 references:
AC-19(a), AC-19(d), AC-19(e), CM-7, MP-2 |
Add noexec Option to Removable Media PartitionsruleThe noexec mount option prevents the direct
execution of binaries on the mounted filesystem.
Preventing the direct execution of binaries from removable media (such as a USB
key) provides a defense against malicious software that may be present on such
untrusted media.
Add the noexec option to the fourth column of
/etc/fstab for the line which controls mounting of
any removable media partitions.
identifiers:
CCE-27196-5, DISA FSO RHEL-06-000271 references:
AC-19(a), AC-19(d), AC-19(e), CM-7, MP-2, 87 |
Add nosuid Option to Removable Media PartitionsruleThe nosuid mount option prevents set-user-identifier (SUID)
and set-group-identifier (SGID) permissions from taking effect. These permissions
allow users to execute binaries with the same permissions as the owner and group
of the file respectively. Users should not be allowed to introduce SUID and SGID
files into the system via partitions mounted from removeable media.
Add the nosuid option to the fourth column of
/etc/fstab for the line which controls mounting of
any removable media partitions.
identifiers:
CCE-27056-1 references:
AC-19(a), AC-19(d), AC-19(e), CM-7, MP-2 |
Add nodev Option to /tmprule
The nodev mount option can be used to prevent device files from
being created in /tmp.
Legitimate character and block devices should not exist
within temporary directories like /tmp.
Add the nodev option to the fourth column of
/etc/fstab for the line which controls mounting of
/tmp.
identifiers:
CCE-26499-4 references:
CM-7, MP-2 |
Add noexec Option to /tmpruleThe noexec mount option can be used to prevent binaries
from being executed out of /tmp.
Add the noexec option to the fourth column of
/etc/fstab for the line which controls mounting of
/tmp.
identifiers:
CCE-26720-3 references:
CM-7, MP-2 |
Add nosuid Option to /tmpruleThe nosuid mount option can be used to prevent
execution of setuid programs in /tmp. The SUID and SGID permissions
should not be required in these world-writable directories.
Add the nosuid option to the fourth column of
/etc/fstab for the line which controls mounting of
/tmp.
identifiers:
CCE-26762-5 references:
CM-7, MP-2 |
Add nodev Option to /dev/shmruleThe nodev mount option can be used to prevent creation
of device files in /dev/shm.
Legitimate character and block devices should not exist
within temporary directories like /dev/shm.
Add the nodev option to the fourth column of
/etc/fstab for the line which controls mounting of
/dev/shm.
identifiers:
CCE-26778-1 references:
CM-7, MP-2 Remediation script:
# Load /etc/fstab's /dev/shm row into DEV_SHM_FSTAB variable separating start &
# end of the filesystem mount options (4-th field) with the '#' character
DEV_SHM_FSTAB=$(sed -n "s/\(.*[[:space:]]\+\/dev\/shm[[:space:]]\+tmpfs[[:space:]]\+\)\([^[:space:]]\+\)/\1#\2#/p" /etc/fstab)
# Save the:
# * 1-th, 2-nd, 3-rd fields into DEV_SHM_HEAD variable
# * 4-th field into DEV_SHM_OPTS variable, and
# * 5-th, and 6-th fields into DEV_SHM_TAIL variable
# splitting DEV_SHM_FSTAB variable value based on the '#' separator
IFS='#' read DEV_SHM_HEAD DEV_SHM_OPTS DEV_SHM_TAIL <<< "$DEV_SHM_FSTAB"
# Replace occurrence of 'defaults' key with the actual list of mount options
# for Red Hat Enterprise Linux 6
DEV_SHM_OPTS=${DEV_SHM_OPTS//defaults/rw,suid,dev,exec,auto,nouser,async,relatime}
# 'dev' option (not prefixed with 'no') present in the list?
echo $DEV_SHM_OPTS | grep -q -P '(?<!no)dev'
if [ $? -eq 0 ]
then
# 'dev' option found, replace with 'nodev'
DEV_SHM_OPTS=${DEV_SHM_OPTS//dev/nodev}
fi
# at least one 'nodev' present in the options list?
echo $DEV_SHM_OPTS | grep -q -v 'nodev'
if [ $? -eq 0 ]
then
# 'nodev' not found yet, append it
DEV_SHM_OPTS="$DEV_SHM_OPTS,nodev"
fi
# DEV_SHM_OPTS now contains final list of mount options. Replace original form of /dev/shm row
# in /etc/fstab with the corrected version
sed -i "s#${DEV_SHM_HEAD}\(.*\)${DEV_SHM_TAIL}#${DEV_SHM_HEAD}${DEV_SHM_OPTS}${DEV_SHM_TAIL}#" /etc/fstab
|
Add noexec Option to /dev/shmruleThe noexec mount option can be used to prevent binaries
from being executed out of /dev/shm.
It can be dangerous to allow the execution of binaries
from world-writable temporary storage directories such as /dev/shm.
Add the noexec option to the fourth column of
/etc/fstab for the line which controls mounting of
/dev/shm.
identifiers:
CCE-26622-1 references:
CM-7, MP-2 Remediation script:
# Load /etc/fstab's /dev/shm row into DEV_SHM_FSTAB variable separating start &
# end of the filesystem mount options (4-th field) with the '#' character
DEV_SHM_FSTAB=$(sed -n "s/\(.*[[:space:]]\+\/dev\/shm[[:space:]]\+tmpfs[[:space:]]\+\)\([^[:space:]]\+\)/\1#\2#/p" /etc/fstab)
# Save the:
# * 1-th, 2-nd, 3-rd fields into DEV_SHM_HEAD variable
# * 4-th field into DEV_SHM_OPTS variable, and
# * 5-th, and 6-th fields into DEV_SHM_TAIL variable
# splitting DEV_SHM_FSTAB variable value based on the '#' separator
IFS='#' read DEV_SHM_HEAD DEV_SHM_OPTS DEV_SHM_TAIL <<< "$DEV_SHM_FSTAB"
# Replace occurrence of 'defaults' key with the actual list of mount options
# for Red Hat Enterprise Linux 6
DEV_SHM_OPTS=${DEV_SHM_OPTS//defaults/rw,suid,dev,exec,auto,nouser,async,relatime}
# 'exec' option (not prefixed with 'no') present in the list?
echo $DEV_SHM_OPTS | grep -q -P '(?<!no)exec'
if [ $? -eq 0 ]
then
# 'exec' option found, replace with 'noexec'
DEV_SHM_OPTS=${DEV_SHM_OPTS//exec/noexec}
fi
# at least one 'noexec' present in the options list?
echo $DEV_SHM_OPTS | grep -q -v 'noexec'
if [ $? -eq 0 ]
then
# 'noexec' not found yet, append it
DEV_SHM_OPTS="$DEV_SHM_OPTS,noexec"
fi
# DEV_SHM_OPTS now contains final list of mount options. Replace original form of /dev/shm row
# in /etc/fstab with the corrected version
sed -i "s#${DEV_SHM_HEAD}\(.*\)${DEV_SHM_TAIL}#${DEV_SHM_HEAD}${DEV_SHM_OPTS}${DEV_SHM_TAIL}#" /etc/fstab
|
Add nosuid Option to /dev/shmruleThe nosuid mount option can be used to prevent execution
of setuid programs in /dev/shm. The SUID and SGID permissions should not
be required in these world-writable directories.
Add the nosuid option to the fourth column of
/etc/fstab for the line which controls mounting of
/dev/shm.
identifiers:
CCE-26486-1 references:
CM-7, MP-2 Remediation script:
# Load /etc/fstab's /dev/shm row into DEV_SHM_FSTAB variable separating start &
# end of the filesystem mount options (4-th field) with the '#' character
DEV_SHM_FSTAB=$(sed -n "s/\(.*[[:space:]]\+\/dev\/shm[[:space:]]\+tmpfs[[:space:]]\+\)\([^[:space:]]\+\)/\1#\2#/p" /etc/fstab)
# Save the:
# * 1-th, 2-nd, 3-rd fields into DEV_SHM_HEAD variable
# * 4-th field into DEV_SHM_OPTS variable, and
# * 5-th, and 6-th fields into DEV_SHM_TAIL variable
# splitting DEV_SHM_FSTAB variable value based on the '#' separator
IFS='#' read DEV_SHM_HEAD DEV_SHM_OPTS DEV_SHM_TAIL <<< "$DEV_SHM_FSTAB"
# Replace occurrence of 'defaults' key with the actual list of mount options
# for Red Hat Enterprise Linux 6
DEV_SHM_OPTS=${DEV_SHM_OPTS//defaults/rw,suid,dev,exec,auto,nouser,async,relatime}
# 'suid' option (not prefixed with 'no') present in the list?
echo $DEV_SHM_OPTS | grep -q -P '(?<!no)suid'
if [ $? -eq 0 ]
then
# 'suid' option found, replace with 'nosuid'
DEV_SHM_OPTS=${DEV_SHM_OPTS//suid/nosuid}
fi
# at least one 'nosuid' present in the options list?
echo $DEV_SHM_OPTS | grep -q -v 'nosuid'
if [ $? -eq 0 ]
then
# 'nosuid' not found yet, append it
DEV_SHM_OPTS="$DEV_SHM_OPTS,nosuid"
fi
# DEV_SHM_OPTS now contains final list of mount options. Replace original form of /dev/shm row
# in /etc/fstab with the corrected version
sed -i "s#${DEV_SHM_HEAD}\(.*\)${DEV_SHM_TAIL}#${DEV_SHM_HEAD}${DEV_SHM_OPTS}${DEV_SHM_TAIL}#" /etc/fstab
|
Bind Mount /var/tmp To /tmpruleThe /var/tmp directory is a world-writable directory.
Bind-mount it to /tmp in order to consolidate temporary storage into
one location protected by the same techniques as /tmp. To do so, edit
/etc/fstab and add the following line:
/tmp /var/tmp none rw,nodev,noexec,nosuid,bind 0 0
See the mount(8) man page for further explanation of bind mounting.
identifiers:
CCE-26582-7 references:
CM-7 Remediation script:# Delete particular /etc/fstab's row if /var/tmp is already configured to
# represent a mount point (for some device or filesystem other than /tmp)
if grep -q -P '.*\/var\/tmp.*' /etc/fstab
then
sed -i '/.*\/var\/tmp.*/d' /etc/fstab
fi
# Bind-mount /var/tmp to /tmp via /etc/fstab (preserving the /etc/fstab form)
printf "%-24s%-24s%-8s%-32s%-3s\n" "/tmp" "/var/tmp" "none" "rw,nodev,noexec,nosuid,bind" "0 0" >> /etc/fstab
|
Restrict Dynamic Mounting and Unmounting of
FilesystemsgroupLinux includes a number of facilities for the automated addition
and removal of filesystems on a running system. These facilities may be
necessary in many environments, but this capability also carries some risk -- whether direct
risk from allowing users to introduce arbitrary filesystems,
or risk that software flaws in the automated mount facility itself could
allow an attacker to compromise the system.
This command can be used to list the types of filesystems that are
available to the currently executing kernel:
$ find /lib/modules/`uname -r`/kernel/fs -type f -name '*.ko'
If these filesystems are not required then they can be explicitly disabled
in a configuratio file in /etc/modprobe.d.
|
contains 7 rules |
Disable Mounting of cramfsrule
To configure the system to prevent the cramfs
kernel module from being loaded, add the following line to a file in the directory /etc/modprobe.d:
install cramfs /bin/true
This effectively prevents usage of this uncommon filesystem.
identifiers:
CCE-26340-0 references:
CM-7 Remediation script:echo "install cramfs /bin/true" > /etc/modprobe.d/cramfs.conf
|
Disable Mounting of freevxfsrule
To configure the system to prevent the freevxfs
kernel module from being loaded, add the following line to a file in the directory /etc/modprobe.d:
install freevxfs /bin/true
This effectively prevents usage of this uncommon filesystem.
identifiers:
CCE-26544-7 references:
CM-7 Remediation script:echo "install freevxfs /bin/true" > /etc/modprobe.d/freevxfs.conf
|
Disable Mounting of jffs2rule
To configure the system to prevent the jffs2
kernel module from being loaded, add the following line to a file in the directory /etc/modprobe.d:
install jffs2 /bin/true
This effectively prevents usage of this uncommon filesystem.
identifiers:
CCE-26670-0 references:
CM-7 Remediation script:echo "install jffs2 /bin/true" > /etc/modprobe.d/jffs2.conf
|
Disable Mounting of hfsrule
To configure the system to prevent the hfs
kernel module from being loaded, add the following line to a file in the directory /etc/modprobe.d:
install hfs /bin/true
This effectively prevents usage of this uncommon filesystem.
identifiers:
CCE-26800-3 references:
CM-7 Remediation script:echo "install hfs /bin/true" > /etc/modprobe.d/hfs.conf
|
Disable Mounting of hfsplusrule
To configure the system to prevent the hfsplus
kernel module from being loaded, add the following line to a file in the directory /etc/modprobe.d:
install hfsplus /bin/true
This effectively prevents usage of this uncommon filesystem.
identifiers:
CCE-26361-6 references:
CM-7 Remediation script:echo "install hfsplus /bin/true" > /etc/modprobe.d/hfsplus.conf
|
Disable Mounting of squashfsrule
To configure the system to prevent the squashfs
kernel module from being loaded, add the following line to a file in the directory /etc/modprobe.d:
install squashfs /bin/true
This effectively prevents usage of this uncommon filesystem.
identifiers:
CCE-26404-4 references:
CM-7 Remediation script:echo "install squashfs /bin/true" > /etc/modprobe.d/squashfs.conf
|
Disable Mounting of udfrule
To configure the system to prevent the udf
kernel module from being loaded, add the following line to a file in the directory /etc/modprobe.d:
install udf /bin/true
This effectively prevents usage of this uncommon filesystem.
identifiers:
CCE-26677-5 references:
CM-7 Remediation script:echo "install udf /bin/true" > /etc/modprobe.d/udf.conf
|
Verify Permissions on Important Files and
DirectoriesgroupPermissions for many files on a system must be set
restrictively to ensure sensitive information is properly protected.
This section discusses important
permission restrictions which can be verified
to ensure that no harmful discrepancies have
arisen. |
contains 19 rules |
Verify Permissions on Files with Local Account Information and CredentialsgroupThe default restrictive permissions for files which act as
important security databases such as passwd, shadow,
group, and gshadow files must be maintained. Many utilities
need read access to the passwd file in order to function properly, but
read access to the shadow file allows malicious attacks against system
passwords, and should never be enabled. |
contains 12 rules |
Verify User Who Owns shadow Filerule
To properly set the owner of /etc/shadow, run the command:
$ sudo chown root /etc/shadow
identifiers:
CCE-26947-2, DISA FSO RHEL-06-000033 references:
AC-6, 225, Test attestation on 20121026 by DS Remediation script:chown root /etc/shadow
|
Verify Group Who Owns shadow Filerule
To properly set the group owner of /etc/shadow, run the command:
$ sudo chgrp root /etc/shadow
identifiers:
CCE-26967-0, DISA FSO RHEL-06-000034 references:
AC-6, 225, Test attestation on 20121026 by DS Remediation script:chgrp root /etc/shadow
|
Verify Permissions on shadow Filerule
To properly set the permissions of /etc/shadow, run the command:
$ sudo chmod 0000 /etc/shadow
identifiers:
CCE-26992-8, DISA FSO RHEL-06-000035 references:
AC-6, 225, Test attestation on 20121026 by DS Remediation script:chmod 0000 /etc/shadow
|
Verify User Who Owns group Filerule
To properly set the owner of /etc/group, run the command:
$ sudo chown root /etc/group
identifiers:
CCE-26822-7, DISA FSO RHEL-06-000042 references:
AC-6, Test attestation on 20121026 by DS Remediation script:chown root /etc/group
|
Verify Group Who Owns group Filerule
To properly set the group owner of /etc/group, run the command:
$ sudo chgrp root /etc/group
identifiers:
CCE-26930-8, DISA FSO RHEL-06-000043 references:
AC-6, 225, Test attestation on 20121026 by DS Remediation script:chgrp root /etc/group
|
Verify Permissions on group Filerule
To properly set the permissions of /etc/group, run the command:
$ sudo chmod 644 /etc/group
identifiers:
CCE-26954-8, DISA FSO RHEL-06-000044 references:
AC-6, 225, Test attestation on 20121026 by DS Remediation script:chmod 644 /etc/group
|
Verify User Who Owns gshadow Filerule
To properly set the owner of /etc/gshadow, run the command:
$ sudo chown root /etc/gshadow
identifiers:
CCE-27026-4, DISA FSO RHEL-06-000036 references:
AC-6, 225, Test attestation on 20121026 by DS Remediation script:chown root /etc/gshadow
|
Verify Group Who Owns gshadow Filerule
To properly set the group owner of /etc/gshadow, run the command:
$ sudo chgrp root /etc/gshadow
identifiers:
CCE-26975-3, DISA FSO RHEL-06-000037 references:
AC-6, 225, Test attestation on 20121026 by DS Remediation script:chgrp root /etc/gshadow
|
Verify Permissions on gshadow Filerule
To properly set the permissions of /etc/gshadow, run the command:
$ sudo chmod 0000 /etc/gshadow
identifiers:
CCE-26951-4, DISA FSO RHEL-06-000038 references:
AC-6, 225, Test attestation on 20121026 by DS Remediation script:chmod 0000 /etc/gshadow
|
Verify User Who Owns passwd Filerule
To properly set the owner of /etc/passwd, run the command:
$ sudo chown root /etc/passwd
identifiers:
CCE-26953-0, DISA FSO RHEL-06-000039 references:
AC-6, 225, Test attestation on 20121026 by DS Remediation script:chown root /etc/passwd
|
Verify Group Who Owns passwd Filerule
To properly set the group owner of /etc/passwd, run the command:
$ sudo chgrp root /etc/passwd
identifiers:
CCE-26856-5, DISA FSO RHEL-06-000040 references:
AC-6, 225, Test attestation on 20121026 by DS Remediation script:chgrp root /etc/passwd
|
Verify Permissions on passwd Filerule
To properly set the permissions of /etc/passwd, run the command:
$ sudo chmod 0644 /etc/passwd
identifiers:
CCE-26868-0, DISA FSO RHEL-06-000041 references:
AC-6, 225, Test attestation on 20121026 by DS Remediation script:chmod 0644 /etc/passwd
|
Verify File Permissions Within Some Important DirectoriesgroupSome directories contain files whose confidentiality or integrity
is notably important and may also be susceptible to misconfiguration over time, particularly if
unpackaged software is installed. As such,
an argument exists to verify that files' permissions within these directories remain
configured correctly and restrictively.
|
contains 1 rule |
Verify that System Executables Have Restrictive Permissionsrule
System executables are stored in the following directories by default:
/bin
/usr/bin
/usr/local/bin
/sbin
/usr/sbin
/usr/local/sbin
All files in these directories should not be group-writable or world-writable.
If any file FILE in these directories is found
to be group-writable or world-writable, correct its permission with the
following command:
$ sudo chmod go-w FILE
identifiers:
CCE-27289-8, DISA FSO RHEL-06-000047 references:
AC-6, 1499 Remediation script:DIRS="/bin /usr/bin /usr/local/bin /sbin /usr/sbin /usr/local/sbin"
for dirPath in $DIRS; do
find $dirPath -perm /022 -exec chmod go-w '{}' \;
done
|
Verify that All World-Writable Directories Have Sticky Bits SetruleWhen the so-called 'sticky bit' is set on a directory,
only the owner of a given file may remove that file from the
directory. Without the sticky bit, any user with write access to a
directory may remove any file in the directory. Setting the sticky
bit prevents users from removing each other's files. In cases where
there is no reason for a directory to be world-writable, a better
solution is to remove that permission rather than to set the sticky
bit. However, if a directory is used by a particular application,
consult that application's documentation instead of blindly
changing modes.
To set the sticky bit on a world-writable directory DIR, run the
following command:
$ sudo chmod +t DIR
identifiers:
CCE-26840-9, DISA FSO RHEL-06-000336 references:
AC-6, Test attestation on 20120929 by swells Remediation script:df --local -P | awk {'if (NR!=1) print $6'} \
| xargs -I '{}' find '{}' -xdev -type d \
\( -perm -0002 -a ! -perm -1000 \) 2>/dev/null \
| xargs chmod a+t
|
Ensure No World-Writable Files ExistruleIt is generally a good idea to remove global (other) write
access to a file when it is discovered. However, check with
documentation for specific applications before making changes.
Also, monitor for recurring world-writable files, as these may be
symptoms of a misconfigured application or user
account. identifiers:
CCE-26910-0, DISA FSO RHEL-06-000282 references:
AC-6 |
Ensure All SGID Executables Are AuthorizedruleThe SGID (set group id) bit should be set only on files that were
installed via authorized means. A straightforward means of identifying
unauthorized SGID files is determine if any were not installed as part of an
RPM package, which is cryptographically verified. Investigate the origin
of any unpackaged SGID files.
identifiers:
CCE-26769-0 references:
AC-6(1) |
Ensure All SUID Executables Are AuthorizedruleThe SUID (set user id) bit should be set only on files that were
installed via authorized means. A straightforward means of identifying
unauthorized SGID files is determine if any were not installed as part of an
RPM package, which is cryptographically verified. Investigate the origin
of any unpackaged SUID files.
identifiers:
CCE-26497-8 references:
AC-6(1) |
Ensure All Files Are Owned by a UserruleIf any files are not owned by a user, then the
cause of their lack of ownership should be investigated.
Following this, the files should be deleted or assigned to an
appropriate user.
identifiers:
CCE-27032-2 references:
AC-6, 224 |
Ensure All Files Are Owned by a GroupruleIf any files are not owned by a group, then the
cause of their lack of group-ownership should be investigated.
Following this, the files should be deleted or assigned to an
appropriate group.
identifiers:
CCE-26872-2 references:
AC-6, 224 |
Restrict Programs from Dangerous Execution PatternsgroupThe recommendations in this section are designed to
ensure that the system's features to protect against potentially
dangerous program execution are activated.
These protections are applied at the system initialization or
kernel level, and defend against certain types of badly-configured
or compromised programs. |
contains 5 rules |
Daemon UmaskgroupThe umask is a per-process setting which limits
the default permissions for creation of new files and directories.
The system includes initialization scripts which set the default umask
for system daemons.
|
contains 1 rule |
Set Daemon UmaskruleThe file /etc/init.d/functions includes initialization
parameters for most or all daemons started at boot time. The default umask of
022 prevents creation of group- or world-writable files. To set the default
umask for daemons, edit the following line, inserting 022 or 027 for
umask appropriately:
umask 027
Setting the umask to too restrictive a setting can cause serious errors at
runtime. Many daemons on the system already individually restrict themselves to
a umask of 077 in their own init scripts.
identifiers:
CCE-27031-4, DISA FSO RHEL-06-000346 references:
AC-6, Test attestation on 20140912 by JL Remediation script:var_umask_for_daemons="027"
grep -q ^umask /etc/init.d/functions && \
sed -i "s/umask.*/umask $var_umask_for_daemons/g" /etc/init.d/functions
if ! [ $? -eq 0 ]; then
echo "umask $var_umask_for_daemons" >> /etc/init.d/functions
fi
|
Disable Core DumpsgroupA core dump file is the memory image of an executable
program when it was terminated by the operating system due to
errant behavior. In most cases, only software developers
legitimately need to access these files. The core dump files may
also contain sensitive information, or unnecessarily occupy large
amounts of disk space.
Once a hard limit is set in /etc/security/limits.conf, a
user cannot increase that limit within his or her own session. If access
to core dumps is required, consider restricting them to only
certain users or groups. See the limits.conf man page for more
information.
The core dumps of setuid programs are further protected. The
sysctl variable fs.suid_dumpable controls whether
the kernel allows core dumps from these programs at all. The default
value of 0 is recommended. |
contains 2 rules |
Disable Core Dumps for All UsersruleTo disable core dumps for all users, add the following line to
/etc/security/limits.conf:
* hard core 0
identifiers:
CCE-27033-0, DISA FSO RHEL-06-000308 references:
SC-5 Remediation script:echo "* hard core 0" >> /etc/security/limits.conf
|
Disable Core Dumps for SUID programsrule
To set the runtime status of the fs.suid_dumpable kernel parameter,
run the following command:
$ sudo sysctl -w fs.suid_dumpable=0
If this is not the system's default value, add the following line to /etc/sysctl.conf:
fs.suid_dumpable = 0
identifiers:
CCE-27044-7 references:
SI-11 Remediation script:#
# Set runtime for fs.suid_dumpable
#
/sbin/sysctl -q -n -w fs.suid_dumpable=0
#
# If fs.suid_dumpable present in /etc/sysctl.conf, change value to "0"
# else, add "fs.suid_dumpable = 0" to /etc/sysctl.conf
#
if grep --silent ^fs.suid_dumpable /etc/sysctl.conf ; then
sed -i 's/^fs.suid_dumpable.*/fs.suid_dumpable = 0/g' /etc/sysctl.conf
else
echo -e "\n# Set fs.suid_dumpable to 0 per security requirements" >> /etc/sysctl.conf
echo "fs.suid_dumpable = 0" >> /etc/sysctl.conf
fi
|
Enable ExecShieldgroupExecShield describes kernel features that provide
protection against exploitation of memory corruption errors such as buffer
overflows. These features include random placement of the stack and other
memory regions, prevention of execution in memory that should only hold data,
and special handling of text buffers. These protections are enabled by default and
controlled through sysctl variables kernel.exec-shield and
kernel.randomize_va_space.
|
contains 2 rules |
Enable ExecShieldrule
To set the runtime status of the kernel.exec-shield kernel parameter,
run the following command:
$ sudo sysctl -w kernel.exec-shield=1
If this is not the system's default value, add the following line to /etc/sysctl.conf:
kernel.exec-shield = 1
identifiers:
CCE-27007-4, DISA FSO RHEL-06-000079 references:
SC-39, 2530, Test attestation on 20121024 by DS Remediation script:#
# Set runtime for kernel.exec-shield
#
/sbin/sysctl -q -n -w kernel.exec-shield=1
#
# If kernel.exec-shield present in /etc/sysctl.conf, change value to "1"
# else, add "kernel.exec-shield = 1" to /etc/sysctl.conf
#
if grep --silent ^kernel.exec-shield /etc/sysctl.conf ; then
sed -i 's/^kernel.exec-shield.*/kernel.exec-shield = 1/g' /etc/sysctl.conf
else
echo -e "\n# Set kernel.exec-shield to 1 per security requirements" >> /etc/sysctl.conf
echo "kernel.exec-shield = 1" >> /etc/sysctl.conf
fi
|
Enable Randomized Layout of Virtual Address Spacerule
To set the runtime status of the kernel.randomize_va_space kernel parameter,
run the following command:
$ sudo sysctl -w kernel.randomize_va_space=2
If this is not the system's default value, add the following line to /etc/sysctl.conf:
kernel.randomize_va_space = 2
identifiers:
CCE-26999-3, DISA FSO RHEL-06-000078 references:
SC-30(2), Test attestation on 20121024 by DS Remediation script:#
# Set runtime for kernel.randomize_va_space
#
/sbin/sysctl -q -n -w kernel.randomize_va_space=2
#
# If kernel.randomize_va_space present in /etc/sysctl.conf, change value to "2"
# else, add "kernel.randomize_va_space = 2" to /etc/sysctl.conf
#
if grep --silent ^kernel.randomize_va_space /etc/sysctl.conf ; then
sed -i 's/^kernel.randomize_va_space.*/kernel.randomize_va_space = 2/g' /etc/sysctl.conf
else
echo -e "\n# Set kernel.randomize_va_space to 2 per security requirements" >> /etc/sysctl.conf
echo "kernel.randomize_va_space = 2" >> /etc/sysctl.conf
fi
|
SELinuxgroupSELinux is a feature of the Linux kernel which can be
used to guard against misconfigured or compromised programs.
SELinux enforces the idea that programs should be limited in what
files they can access and what actions they can take.
The default SELinux policy, as configured on Red Hat Enterprise Linux 6, has been
sufficiently developed and debugged that it should be usable on
almost any Red Hat machine with minimal configuration and a small
amount of system administrator training. This policy prevents
system services - including most of the common network-visible
services such as mail servers, FTP servers, and DNS servers - from
accessing files which those services have no valid reason to
access. This action alone prevents a huge amount of possible damage
from network attacks against services, from trojaned software, and
so forth.
This guide recommends that SELinux be enabled using the
default (targeted) policy on every Red Hat system, unless that
system has unusual requirements which make a stronger policy
appropriate.
|
contains 6 rules |
Ensure SELinux Not Disabled in /etc/grub.confruleSELinux can be disabled at boot time by an argument in
/etc/grub.conf.
Remove any instances of selinux=0 from the kernel arguments in that
file to prevent SELinux from being disabled at boot.
identifiers:
CCE-26956-3, DISA FSO RHEL-06-000017 references:
AC-3, AC-3(3), AC-6, AU-9, 22, 32, Test attestation on 20121024 by DS Remediation script:sed -i --follow-symlinks "s/selinux=0//gI" /etc/grub.conf
sed -i --follow-symlinks "s/enforcing=0//gI" /etc/grub.conf
|
Ensure SELinux State is EnforcingruleThe SELinux state should be set to enforcing at
system boot time. In the file /etc/selinux/config, add or correct the
following line to configure the system to boot into enforcing mode:
SELINUX=enforcing
identifiers:
CCE-26969-6, DISA FSO RHEL-06-000020 references:
AC-3, AC-3(3), AC-4, AC-6, AU-9, 22, 32, 26, Test attestation on 20121024 by DS Remediation script:var_selinux_state="enforcing"
grep -q ^SELINUX= /etc/selinux/config && \
sed -i "s/SELINUX=.*/SELINUX=$var_selinux_state/g" /etc/selinux/config
if ! [ $? -eq 0 ]; then
echo "SELINUX=$var_selinux_state" >> /etc/selinux/config
fi
|
Configure SELinux PolicyruleThe SELinux targeted policy is appropriate for
general-purpose desktops and servers, as well as systems in many other roles.
To configure the system to use this policy, add or correct the following line
in /etc/selinux/config:
SELINUXTYPE=targeted
Other policies, such as mls, provide additional security labeling
and greater confinement but are not compatible with many general-purpose
use cases.
identifiers:
CCE-26875-5, DISA FSO RHEL-06-000023 references:
AC-3, AC-3(3), AC-4, AC-6, AU-9, 22, 32, Test attestation on 20121024 by DS Remediation script:var_selinux_policy_name="targeted"
grep -q ^SELINUXTYPE /etc/selinux/config && \
sed -i "s/SELINUXTYPE=.*/SELINUXTYPE=$var_selinux_policy_name/g" /etc/selinux/config
if ! [ $? -eq 0 ]; then
echo "SELINUXTYPE=$var_selinux_policy_name" >> /etc/selinux/config
fi
|
Uninstall setroubleshoot PackageruleThe SETroubleshoot service notifies desktop users of SELinux
denials. The service provides information around configuration errors,
unauthorized intrusions, and other potential errors.
The setroubleshoot package can be removed with the following command:
$ sudo yum erase setroubleshoot
identifiers:
CCE- |
Uninstall mcstrans PackageruleThe mcstransd daemon provides category label information
to client processes requesting information. The label translations are defined
in /etc/selinux/targeted/setrans.conf.
The mcstrans package can be removed with the following command:
$ sudo yum erase mcstrans
identifiers:
CCE- |
Ensure No Daemons are Unconfined by SELinuxrule
Daemons for which the SELinux policy does not contain rules will inherit the
context of the parent process. Because daemons are launched during
startup and descend from the init process, they inherit the initrc_t context.
To check for unconfined daemons, run the following command:
$ sudo ps -eZ | egrep "initrc" | egrep -vw "tr|ps|egrep|bash|awk" | tr ':' ' ' | awk '{ print $NF }'
It should produce no output in a well-configured system.
identifiers:
CCE-27111-4 references:
AC-6, AU-9, CM-7 |
Account and Access ControlgroupIn traditional Unix security, if an attacker gains
shell access to a certain login account, they can perform any action
or access any file to which that account has access. Therefore,
making it more difficult for unauthorized people to gain shell
access to accounts, particularly to privileged accounts, is a
necessary part of securing a system. This section introduces
mechanisms for restricting access to accounts under
Red Hat Enterprise Linux 6. |
contains 26 rules |
Protect Accounts by Restricting Password-Based LogingroupConventionally, Unix shell accounts are accessed by
providing a username and password to a login program, which tests
these values for correctness using the /etc/passwd and
/etc/shadow files. Password-based login is vulnerable to
guessing of weak passwords, and to sniffing and man-in-the-middle
attacks against passwords entered over a network or at an insecure
console. Therefore, mechanisms for accessing accounts by entering
usernames and passwords should be restricted to those which are
operationally necessary. |
contains 12 rules |
Restrict Root Loginsgroup
Direct root logins should be allowed only for emergency use.
In normal situations, the administrator should access the system
via a unique unprivileged account, and then use su or sudo to execute
privileged commands. Discouraging administrators from accessing the
root account directly ensures an audit trail in organizations with
multiple administrators. Locking down the channels through which
root can connect directly also reduces opportunities for
password-guessing against the root account. The login program
uses the file /etc/securetty to determine which interfaces
should allow root logins.
The virtual devices /dev/console
and /dev/tty* represent the system consoles (accessible via
the Ctrl-Alt-F1 through Ctrl-Alt-F6 keyboard sequences on a default
installation). The default securetty file also contains /dev/vc/*.
These are likely to be deprecated in most environments, but may be retained
for compatibility. Root should also be prohibited from connecting
via network protocols. Other sections of this document
include guidance describing how to prevent root from logging in via SSH.
|
contains 4 rules |
Direct root Logins Not AllowedruleTo further limit access to the root account, administrators
can disable root logins at the console by editing the /etc/securetty file.
This file lists all devices the root user is allowed to login to. If the file does
not exist at all, the root user can login through any communication device on the
system, whether via the console or via a raw network interface. This is dangerous
as user can login to his machine as root via Telnet, which sends the password in
plain text over the network. By default, Red Hat Enteprise Linux's
/etc/securetty file only allows the root user to login at the console
physically attached to the machine. To prevent root from logging in, remove the
contents of this file. To prevent direct root logins, remove the contents of this
file by typing the following command:
$ sudo echo > /etc/securetty
identifiers:
CCE-26891-2 references:
IA-2(1), Test attestation on 20121024 by DS |
Ensure that System Accounts Do Not Run a Shell Upon Loginrule
Some accounts are not associated with a human
user of the system, and exist to perform some administrative
function. Should an attacker be able to log into these accounts,
they should not be granted access to a shell.
The login shell for each local account is stored in the last field of each line
in /etc/passwd. System accounts are those user accounts with a user ID less than
500. The user ID is stored in the third field.
If any system account SYSACCT (other than root) has a login shell,
disable it with the command:
$ sudo usermod -s /sbin/nologin SYSACCT
identifiers:
CCE-26966-2 references:
AC-2, 178, Test attestation on 20121024 by DS |
Verify Only Root Has UID 0rule
If any account other than root has a UID of 0,
this misconfiguration should be investigated and the
accounts other than root should be removed or have their UID changed.
identifiers:
CCE-26971-2, DISA FSO RHEL-06-000032 references:
AC-6, IA-2(1), 366, Test attestation on 20121024 by DS Remediation script:awk -F: '$3 == 0 && $1 != "root" { print $1 }' /etc/passwd | xargs passwd -l
|
Root Path Must Be Vendor Defaultrule
Assuming root shell is bash, edit the following files:
~/.profile
~/.bashrc
Change any PATH variables to the vendor default for root and remove any
empty PATH entries or references to relative paths.
identifiers:
CCE-27125-4 references:
SA-8, Test attestation on 20121024 by DS |
Verify Proper Storage and Existence of Password
Hashesgroup
By default, password hashes for local accounts are stored
in the second field (colon-separated) in
/etc/shadow. This file should be readable only by
processes running with root credentials, preventing users from
casually accessing others' password hashes and attempting
to crack them.
However, it remains possible to misconfigure the system
and store password hashes
in world-readable files such as /etc/passwd, or
to even store passwords themselves in plaintext on the system.
Using system-provided tools for password change/creation
should allow administrators to avoid such misconfiguration.
|
contains 3 rules |
Prevent Log In to Accounts With Empty PasswordruleIf an account is configured for password authentication
but does not have an assigned password, it may be possible to log
onto the account without authentication. Remove any instances of the nullok
option in /etc/pam.d/system-auth to
prevent logins with empty passwords.
identifiers:
CCE-27038-9, DISA FSO RHEL-06-000030 references:
IA-5(b), IA-5(c), IA-5(1)(a), Test attestation on 20121024 by DS Remediation script:sed --follow-symlinks -i 's/\<nullok\>//g' /etc/pam.d/system-auth
|
All GIDs referenced in /etc/passwd must be defined in /etc/grouprule
Add a group to the system for each GID referenced without a corresponding group.
identifiers:
CCE-27379-7, DISA FSO RHEL-06-000294 references:
366, Test attestation on 20121024 by DS |
Verify No netrc Files ExistruleThe .netrc files contain login information
used to auto-login into FTP servers and reside in the user's home
directory. These files may contain unencrypted passwords to
remote FTP servers making them susceptible to access by unauthorized
users and should not be used. Any .netrc files should be removed.
identifiers:
CCE-27225-2, DISA FSO RHEL-06-000347 references:
IA-5(h), AC-3, 196 |
Set Password Expiration ParametersgroupThe file /etc/login.defs controls several
password-related settings. Programs such as passwd,
su, and
login consult /etc/login.defs to determine
behavior with regard to password aging, expiration warnings,
and length. See the man page login.defs(5) for more information.
Users should be forced to change their passwords, in order to
decrease the utility of compromised passwords. However, the need to
change passwords often should be balanced against the risk that
users will reuse or write down passwords if forced to change them
too often. Forcing password changes every 90-360 days, depending on
the environment, is recommended. Set the appropriate value as
PASS_MAX_DAYS and apply it to existing accounts with the
-M flag.
The PASS_MIN_DAYS (-m) setting prevents password
changes for 7 days after the first change, to discourage password
cycling. If you use this setting, train users to contact an administrator
for an emergency password change in case a new password becomes
compromised. The PASS_WARN_AGE (-W) setting gives
users 7 days of warnings at login time that their passwords are about to expire.
For example, for each existing human user USER, expiration parameters
could be adjusted to a 180 day maximum password age, 7 day minimum password
age, and 7 day warning period with the following command:
$ sudo chage -M 180 -m 7 -W 7 USER
|
contains 3 rules |
Set Password Minimum AgeruleTo specify password minimum age for new accounts,
edit the file /etc/login.defs
and add or correct the following line:
PASS_MIN_DAYS 7
A value of 1 day is considered for sufficient for many
environments.
The DoD requirement is 1.
identifiers:
CCE-27013-2, DISA FSO RHEL-06-000051 references:
IA-5(f), IA-5(1)(d), 198, Test attestation on 20121026 by DS Remediation script:var_accounts_minimum_age_login_defs="7"
grep -q ^PASS_MIN_DAYS /etc/login.defs && \
sed -i "s/PASS_MIN_DAYS.*/PASS_MIN_DAYS $var_accounts_minimum_age_login_defs/g" /etc/login.defs
if ! [ $? -eq 0 ]; then
echo "PASS_MIN_DAYS $var_accounts_minimum_age_login_defs" >> /etc/login.defs
fi
|
Set Password Maximum AgeruleTo specify password maximum age for new accounts,
edit the file /etc/login.defs
and add or correct the following line:
PASS_MAX_DAYS 90
A value of 180 days is sufficient for many environments.
The DoD requirement is 60.
identifiers:
CCE-26985-2, DISA FSO RHEL-06-000053 references:
IA-5(f), IA-5(g), IA-5(1)(d), 180, 199, 76, Test attestation on 20121026 by DS Remediation script:var_accounts_maximum_age_login_defs="90"
grep -q ^PASS_MAX_DAYS /etc/login.defs && \
sed -i "s/PASS_MAX_DAYS.*/PASS_MAX_DAYS $var_accounts_maximum_age_login_defs/g" /etc/login.defs
if ! [ $? -eq 0 ]; then
echo "PASS_MAX_DAYS $var_accounts_maximum_age_login_defs" >> /etc/login.defs
fi
|
Set Password Warning AgeruleTo specify how many days prior to password
expiration that a warning will be issued to users,
edit the file /etc/login.defs and add or correct
the following line:
PASS_WARN_AGE 7
The DoD requirement is 7.
identifiers:
CCE-26988-6, DISA FSO RHEL-06-000054 references:
AC-2(2), IA-5(f), Test attestation on 20121026 by DS Remediation script:var_accounts_password_warn_age_login_defs="7"
grep -q ^PASS_WARN_AGE /etc/login.defs && \
sed -i "s/PASS_WARN_AGE.*/PASS_WARN_AGE $var_accounts_password_warn_age_login_defs/g" /etc/login.defs
if ! [ $? -eq 0 ]; then
echo "PASS_WARN_AGE $var_accounts_password_warn_age_login_defs" >> /etc/login.defs
fi
|
Set Account Expiration ParametersgroupAccounts can be configured to be automatically disabled
after a certain time period,
meaning that they will require administrator interaction to become usable again.
Expiration of accounts after inactivity can be set for all accounts by default
and also on a per-account basis, such as for accounts that are known to be temporary.
To configure automatic expiration of an account following
the expiration of its password (that is, after the password has expired and not been changed),
run the following command, substituting NUM_DAYS and USER appropriately:
$ sudo chage -I NUM_DAYS USER
Accounts, such as temporary accounts, can also be configured to expire on an explicitly-set date with the
-E option.
The file /etc/default/useradd controls
default settings for all newly-created accounts created with the system's
normal command line utilities.
|
contains 2 rules |
Set Account Expiration Following InactivityruleTo specify the number of days after a password expires (which
signifies inactivity) until an account is permanently disabled, add or correct
the following lines in /etc/default/useradd, substituting
NUM_DAYS appropriately:
INACTIVE=UNDEFINED_SUB
A value of 35 is recommended.
If a password is currently on the
verge of expiration, then 35 days remain until the account is automatically
disabled. However, if the password will not expire for another 60 days, then 95
days could elapse until the account would be automatically disabled. See the
useradd man page for more information. Determining the inactivity
timeout must be done with careful consideration of the length of a "normal"
period of inactivity for users in the particular environment. Setting
the timeout too low incurs support costs and also has the potential to impact
availability of the system to legitimate users.
identifiers:
CCE-27283-1, DISA FSO RHEL-06-000334 references:
AC-2(2), AC-2(3), 16, 17, 795 Remediation script:var_account_disable_post_pw_expiration="35"
grep -q ^INACTIVE /etc/default/useradd && \
sed -i "s/INACTIVE.*/INACTIVE=$var_account_disable_post_pw_expiration/g" /etc/default/useradd
if ! [ $? -eq 0 ]; then
echo "INACTIVE=$var_account_disable_post_pw_expiration" >> /etc/default/useradd
fi
|
Ensure All Accounts on the System Have Unique Namesrule
Change usernames, or delete accounts, so each has a unique name.
identifiers:
CCE-27609-7, DISA FSO RHEL-06-000296 references:
770, 804 |
Protect Accounts by Configuring PAMgroupPAM, or Pluggable Authentication Modules, is a system
which implements modular authentication for Linux programs. PAM provides
a flexible and configurable architecture for authentication, and it should be configured
to minimize exposure to unnecessary risk. This section contains
guidance on how to accomplish that.
PAM is implemented as a set of shared objects which are
loaded and invoked whenever an application wishes to authenticate a
user. Typically, the application must be running as root in order
to take advantage of PAM, because PAM's modules often need to be able
to access sensitive stores of account information, such as /etc/shadow.
Traditional privileged network listeners
(e.g. sshd) or SUID programs (e.g. sudo) already meet this
requirement. An SUID root application, userhelper, is provided so
that programs which are not SUID or privileged themselves can still
take advantage of PAM.
PAM looks in the directory /etc/pam.d for
application-specific configuration information. For instance, if
the program login attempts to authenticate a user, then PAM's
libraries follow the instructions in the file /etc/pam.d/login
to determine what actions should be taken.
One very important file in /etc/pam.d is
/etc/pam.d/system-auth. This file, which is included by
many other PAM configuration files, defines 'default' system authentication
measures. Modifying this file is a good way to make far-reaching
authentication changes, for instance when implementing a
centralized authentication service. |
contains 2 rules |
Set Lockouts for Failed Password AttemptsgroupThe pam_faillock PAM module provides the capability to
lock out user accounts after a number of failed login attempts. Its
documentation is available in
/usr/share/doc/pam-VERSION/txts/README.pam_faillock.
|
contains 2 rules |
Set Deny For Failed Password Attemptsrule
To configure the system to lock out accounts after a number of incorrect login
attempts using pam_faillock.so, modify the content of both
/etc/pam.d/system-auth and /etc/pam.d/password-auth as follows:
Add the following line immediately before the pam_unix.so statement in the AUTH section:
auth required pam_faillock.so preauth silent deny=3 unlock_time=604800 fail_interval=900 Add the following line immediately after the pam_unix.so statement in the AUTH section:
auth [default=die] pam_faillock.so authfail deny=3 unlock_time=604800 fail_interval=900 Add the following line immediately before the pam_unix.so statement in the ACCOUNT section:
account required pam_faillock.so
identifiers:
CCE-26844-1, DISA FSO RHEL-06-000061 references:
AC-7(a), 44 Remediation script:var_accounts_passwords_pam_faillock_deny="3"
AUTH_FILES[0]="/etc/pam.d/system-auth"
AUTH_FILES[1]="/etc/pam.d/password-auth"
for pamFile in "${AUTH_FILES[@]}"
do
# pam_faillock.so already present?
if grep -q "^auth.*pam_faillock.so.*" $pamFile; then
# pam_faillock.so present, deny directive present?
if grep -q "^auth.*[default=die].*pam_faillock.so.*authfail.*deny=" $pamFile; then
# both pam_faillock.so & deny present, just correct deny directive value
sed -i --follow-symlink "s/\(^auth.*required.*pam_faillock.so.*preauth.*silent.*\)\(deny *= *\).*/\1\2$var_accounts_passwords_pam_faillock_deny/" $pamFile
sed -i --follow-symlink "s/\(^auth.*[default=die].*pam_faillock.so.*authfail.*\)\(deny *= *\).*/\1\2$var_accounts_passwords_pam_faillock_deny/" $pamFile
# pam_faillock.so present, but deny directive not yet
else
# append correct deny value to appropriate places
sed -i --follow-symlink "/^auth.*required.*pam_faillock.so.*preauth.*silent.*/ s/$/ deny=$var_accounts_passwords_pam_faillock_deny/" $pamFile
sed -i --follow-symlink "/^auth.*[default=die].*pam_faillock.so.*authfail.*/ s/$/ deny=$var_accounts_passwords_pam_faillock_deny/" $pamFile
fi
# pam_faillock.so not present yet
else
# insert pam_faillock.so preauth & authfail rows with proper value of the 'deny' option
sed -i --follow-symlink "/^auth.*sufficient.*pam_unix.so.*/i auth required pam_faillock.so preauth silent deny=$var_accounts_passwords_pam_faillock_deny" $pamFile
sed -i --follow-symlink "/^auth.*sufficient.*pam_unix.so.*/a auth [default=die] pam_faillock.so authfail deny=$var_accounts_passwords_pam_faillock_deny" $pamFile
sed -i --follow-symlink "/^account.*required.*pam_unix.so/i account required pam_faillock.so" $pamFile
fi
done
|
Limit Password ReuseruleDo not allow users to reuse recent passwords. This can
be accomplished by using the remember option for the pam_unix PAM
module. In the file /etc/pam.d/system-auth, append remember=5 to the
line which refers to the pam_unix.so module, as shown:
password sufficient pam_unix.so existing_options remember=5
The DoD STIG requirement is 5 passwords. identifiers:
CCE-26741-9, DISA FSO RHEL-06-000274 references:
IA-5(f), IA-5(1)(e), 200, Test attestation on 20121024 by DS Remediation script:var_password_pam_unix_remember="5"
if grep -q "remember=" /etc/pam.d/system-auth; then
sed -i --follow-symlink "s/\(remember *= *\).*/\1$var_password_pam_unix_remember/" /etc/pam.d/system-auth
else
sed -i --follow-symlink "/^password[[:space:]]\+sufficient[[:space:]]\+pam_unix.so/ s/$/ remember=$var_password_pam_unix_remember/" /etc/pam.d/system-auth
fi
|
Secure Session Configuration Files for Login AccountsgroupWhen a user logs into a Unix account, the system
configures the user's session by reading a number of files. Many of
these files are located in the user's home directory, and may have
weak permissions as a result of user error or misconfiguration. If
an attacker can modify or even read certain types of account
configuration information, they can often gain full access to the
affected user's account. Therefore, it is important to test and
correct configuration file permissions for interactive accounts,
particularly those of privileged users such as root or system
administrators. |
contains 3 rules |
Ensure that Users Have Sensible Umask Valuesgroup
The umask setting controls the default permissions
for the creation of new files.
With a default umask setting of 077, files and directories
created by users will not be readable by any other user on the
system. Users who wish to make specific files group- or
world-readable can accomplish this by using the chmod command.
Additionally, users can make all their files readable to their
group by default by setting a umask of 027 in their shell
configuration files. If default per-user groups exist (that is, if
every user has a default group whose name is the same as that
user's username and whose only member is the user), then it may
even be safe for users to select a umask of 007, making it very
easy to intentionally share files with groups of which the user is
a member.
|
contains 2 rules |
Ensure the Default Bash Umask is Set Correctlyrule
To ensure the default umask for users of the Bash shell is set properly,
add or correct the umask setting in /etc/bashrc to read
as follows:
umask 027
identifiers:
CCE-26917-5, DISA FSO RHEL-06-000342 references:
SA-8, 366, Test attestation on 20140912 by JL Remediation script:var_accounts_user_umask="027"
grep -q umask /etc/bashrc && \
sed -i "s/umask.*/umask $var_accounts_user_umask/g" /etc/bashrc
if ! [ $? -eq 0 ]; then
echo "umask $var_accounts_user_umask" >> /etc/bashrc
fi
|
Ensure the Default Umask is Set Correctly in /etc/profilerule
To ensure the default umask controlled by /etc/profile is set properly,
add or correct the umask setting in /etc/profile to read as follows:
umask 027
identifiers:
CCE-26669-2, DISA FSO RHEL-06-000344 references:
SA-8, 366, Test attestation on 20120929 by swells Remediation script:var_accounts_user_umask="027"
grep -q umask /etc/profile && \
sed -i "s/umask.*/umask $var_accounts_user_umask/g" /etc/profile
if ! [ $? -eq 0 ]; then
echo "umask $var_accounts_user_umask" >> /etc/profile
fi
|
Ensure that User Home Directories are not Group-Writable or World-ReadableruleFor each human user of the system, view the
permissions of the user's home directory:
$ sudo ls -ld /home/USER
Ensure that the directory is not group-writable and that it
is not world-readable. If necessary, repair the permissions:
$ sudo chmod g-w /home/USER
$ sudo chmod o-rwx /home/USER
identifiers:
CCE-26981-1 references:
AC-6(7) |
Protect Physical Console AccessgroupIt is impossible to fully protect a system from an
attacker with physical access, so securing the space in which the
system is located should be considered a necessary step. However,
there are some steps which, if taken, make it more difficult for an
attacker to quickly or undetectably modify a system from its
console. |
contains 6 rules |
Set Boot Loader PasswordgroupDuring the boot process, the boot loader is
responsible for starting the execution of the kernel and passing
options to it. The boot loader allows for the selection of
different kernels - possibly on different partitions or media.
The default Red Hat Enterprise Linux boot loader for x86 systems is called GRUB.
Options it can pass to the kernel include single-user mode, which
provides root access without any authentication, and the ability to
disable SELinux. To prevent local users from modifying the boot
parameters and endangering security, protect the boot loader configuration
with a password and ensure its configuration file's permissions
are set properly.
|
contains 4 rules |
Verify /etc/grub.conf User OwnershipruleThe file /etc/grub.conf should
be owned by the root user to prevent destruction
or modification of the file.
To properly set the owner of /etc/grub.conf, run the command:
$ sudo chown root /etc/grub.conf
identifiers:
CCE-26995-1, DISA FSO RHEL-06-000065 references:
AC-6(7), 225, Test attestation on 20121026 by DS Remediation script:chown root /etc/grub.conf
|
Verify /etc/grub.conf Group OwnershipruleThe file /etc/grub.conf should
be group-owned by the root group to prevent
destruction or modification of the file.
To properly set the group owner of /etc/grub.conf, run the command:
$ sudo chgrp root /etc/grub.conf
identifiers:
CCE-27022-3, DISA FSO RHEL-06-000066 references:
AC-6(7), 225, Test attestation on 20121026 by DS Remediation script:chgrp root /etc/grub.conf
|
Verify /boot/grub/grub.conf PermissionsruleFile permissions for /boot/grub/grub.conf should be set to 600, which
is the default.
To properly set the permissions of /boot/grub/grub.conf, run the command:
$ sudo chmod 600 /boot/grub/grub.conf
identifiers:
CCE-26949-8, DISA FSO RHEL-06-000067 references:
AC-6(7), 225, Test attestation on 20121026 by DS Remediation script:chmod 600 /boot/grub/grub.conf
|
Set Boot Loader PasswordruleThe grub boot loader should have password protection
enabled to protect boot-time settings.
To do so, select a password and then generate a hash from it by running the following command:
$ grub-crypt --sha-512
When prompted to enter a password, insert the following line into /etc/grub.conf
immediately after the header comments. (Use the output from grub-crypt as the
value of password-hash):
password --encrypted password-hash
NOTE: To meet FISMA Moderate, the bootloader password MUST differ from the root password.
identifiers:
CCE-26911-8, DISA FSO RHEL-06-000068 references:
IA-2(1), IA-5(e) AC-3, 213, Test attestation on 20121026 by DS |
Require Authentication for Single User ModeruleSingle-user mode is intended as a system recovery
method, providing a single user root access to the system by
providing a boot option at startup. By default, no authentication
is performed if single-user mode is selected.
To require entry of the root password even if the system is
started in single-user mode, add or correct the following line in the
file /etc/sysconfig/init:
SINGLE=/sbin/sulogin
identifiers:
CCE-27040-5, DISA FSO RHEL-06-000069 references:
IA-2(1), AC-3, 213, Test attestation on 20121024 by DS Remediation script:grep -q ^SINGLE /etc/sysconfig/init && \
sed -i "s/SINGLE.*/SINGLE=\/sbin\/sulogin/g" /etc/sysconfig/init
if ! [ $? -eq 0 ]; then
echo "SINGLE=/sbin/sulogin" >> /etc/sysconfig/init
fi
|
Disable Interactive Bootrule
To disable the ability for users to perform interactive startups,
edit the file /etc/sysconfig/init.
Add or correct the line:
PROMPT=no
The PROMPT option allows the console user to perform an
interactive system startup, in which it is possible to select the
set of services which are started on boot.
identifiers:
CCE-27043-9, DISA FSO RHEL-06-000070 references:
SC-2, AC-3, 213, Test attestation on 20121024 by DS Remediation script:grep -q ^PROMPT /etc/sysconfig/init && \
sed -i "s/PROMPT.*/PROMPT=no/g" /etc/sysconfig/init
if ! [ $? -eq 0 ]; then
echo "PROMPT=no" >> /etc/sysconfig/init
fi
|
Warning Banners for System AccessesgroupEach system should expose as little information about
itself as possible.
System banners, which are typically displayed just before a
login prompt, give out information about the service or the host's
operating system. This might include the distribution name and the
system kernel version, and the particular version of a network
service. This information can assist intruders in gaining access to
the system as it can reveal whether the system is running
vulnerable software. Most network services can be configured to
limit what information is displayed.
Many organizations implement security policies that require a
system banner provide notice of the system's ownership, provide
warning to unauthorized users, and remind authorized users of their
consent to monitoring. |
contains 3 rules |
Implement a GUI Warning BannergroupIn the default graphical environment, users logging
directly into the system are greeted with a login screen provided
by the GNOME Display Manager (GDM). The warning banner should be
displayed in this graphical environment for these users.
The following sections describe how to configure the GDM login
banner.
|
contains 2 rules |
Enable GUI Warning Bannerrule
To enable displaying a login warning banner in the GNOME
Display Manager's login screen, run the following command:
$ sudo gconftool-2 --direct \
--config-source xml:readwrite:/etc/gconf/gconf.xml.mandatory \
--type bool \
--set /apps/gdm/simple-greeter/banner_message_enable true
To display a banner, this setting must be enabled and then
banner text must also be set.
identifiers:
CCE-27195-7, DISA FSO RHEL-06-000324 references:
AC-8(a), AC-8(b), AC-8(c), 48, 50 Remediation script:# Install GConf2 package if not installed
if ! rpm -q GConf2; then
yum -y install GConf2
fi
# Enable displaying of a login warning banner in the GNOME Display Manager's
# login screen
gconftool-2 --direct \
--config-source "xml:readwrite:/etc/gconf/gconf.xml.mandatory" \
--type bool \
--set /apps/gdm/simple-greeter/banner_message_enable true
|
Set GUI Warning Banner Textrule
To set the text shown by the GNOME Display Manager
in the login screen, run the following command:
$ sudo gconftool-2 --direct \
--config-source xml:readwrite:/etc/gconf/gconf.xml.mandatory \
--type string \
--set /apps/gdm/simple-greeter/banner_message_text \
"Text of the warning banner here"
When entering a warning banner that spans several lines, remember
to begin and end the string with ". This command writes
directly either to the /etc/gconf/gconf.xml.mandatory/%gconf-tree.xml
if it exists or to the file /etc/gconf/gconf.xml.mandatory/apps/gdm/simple-greeter/%gconf.xml.
Either of these files can later be edited directly if necessary.
identifiers:
CCE-27017-3, DISA FSO RHEL-06-000326 references:
AC-8(a), AC-8(b), AC-8(c), 48, 1384, 1385, 1386, 1387, 1388 Remediation script:login_banner_text="(N/A)"
# Install GConf2 package if not installed
if ! rpm -q GConf2; then
yum -y install GConf2
fi
# Expand the login_banner_text value - there was a regular-expression
# matching various banners, needs to be expanded
banner_expanded=$(echo "$login_banner_text" | sed 's/\[\\s\\n\][*+]/ /g;s/\\//g;')
# Set the text shown by the GNOME Display Manager in the login screen
gconftool-2 --direct \
--config-source "xml:readwrite:/etc/gconf/gconf.xml.mandatory" \
--type string \
--set /apps/gdm/simple-greeter/banner_message_text "${banner_expanded}"
|
Modify the System Login Bannerrule
To configure the system login banner:
Edit /etc/issue. Replace the default text with a message
compliant with the local site policy or a legal disclaimer.
The DoD required text is either:
You are accessing a U.S. Government (USG) Information System (IS) that is
provided for USG-authorized use only. By using this IS (which includes any
device attached to this IS), you consent to the following conditions:
-The USG routinely intercepts and monitors communications on this IS for purposes
including, but not limited to, penetration testing, COMSEC monitoring, network
operations and defense, personnel misconduct (PM), law enforcement (LE), and
counterintelligence (CI) investigations.
-At any time, the USG may inspect and seize data stored on this IS.
-Communications using, or data stored on, this IS are not private, are subject
to routine monitoring, interception, and search, and may be disclosed or used
for any USG-authorized purpose.
-This IS includes security measures (e.g., authentication and access controls)
to protect USG interests -- not for your personal benefit or privacy.
-Notwithstanding the above, using this IS does not constitute consent to PM, LE or CI investigative
searching or monitoring of the content of privileged communications, or work
product, related to personal representation or services by attorneys,
psychotherapists, or clergy, and their assistants. Such communications and work
product are private and confidential. See User Agreement for details.
OR:
I've read & consent to terms in IS user agreem't.
identifiers:
CCE-26974-6, DISA FSO RHEL-06-000073 references:
AC-8(a), AC-8(b), AC-8(c), 48, 1384, 1385, 1386, 1387, 1388, Test attestation on 20121026 by DS Remediation script:login_banner_text="(N/A)"
# There was a regular-expression matching various banners, needs to be expanded
expanded=$(echo "$login_banner_text" | sed 's/\[\\s\\n\][+*]/ /g;s/\\//g;s/[^-]- /\n\n-/g')
formatted=$(echo "$expanded" | fold -sw 80)
cat <<EOF >/etc/issue
$formatted
EOF
printf "\n" >> /etc/issue
|
Network Configuration and FirewallsgroupMost machines must be connected to a network of some
sort, and this brings with it the substantial risk of network
attack. This section discusses the security impact of decisions
about networking which must be made when configuring a system.
This section also discusses firewalls, network access
controls, and other network security frameworks, which allow
system-level rules to be written that can limit an attackers' ability
to connect to your system. These rules can specify that network
traffic should be allowed or denied from certain IP addresses,
hosts, and networks. The rules can also specify which of the
system's network services are available to particular hosts or
networks. |
contains 26 rules |
Kernel Parameters Which Affect NetworkinggroupThe sysctl utility is used to set
parameters which affect the operation of the Linux kernel. Kernel parameters
which affect networking and have security implications are described here.
|
contains 15 rules |
Network Parameters for Hosts OnlygroupIf the system is not going to be used as a router, then setting certain
kernel parameters ensure that the host will not perform routing
of network traffic. |
contains 3 rules |
Disable Kernel Parameter for Sending ICMP Redirects by Defaultrule
To set the runtime status of the net.ipv4.conf.default.send_redirects kernel parameter,
run the following command:
$ sudo sysctl -w net.ipv4.conf.default.send_redirects=0
If this is not the system's default value, add the following line to /etc/sysctl.conf:
net.ipv4.conf.default.send_redirects = 0
identifiers:
CCE-27001-7, DISA FSO RHEL-06-000080 references:
AC-4, CM-7, SC-5, SC-7, 1551, Test attestation on 20121024 by DS Remediation script:#
# Set runtime for net.ipv4.conf.default.send_redirects
#
/sbin/sysctl -q -n -w net.ipv4.conf.default.send_redirects=0
#
# If net.ipv4.conf.default.send_redirects present in /etc/sysctl.conf, change value to "0"
# else, add "net.ipv4.conf.default.send_redirects = 0" to /etc/sysctl.conf
#
if grep --silent ^net.ipv4.conf.default.send_redirects /etc/sysctl.conf ; then
sed -i 's/^net.ipv4.conf.default.send_redirects.*/net.ipv4.conf.default.send_redirects = 0/g' /etc/sysctl.conf
else
echo -e "\n# Set net.ipv4.conf.default.send_redirects to 0 per security requirements" >> /etc/sysctl.conf
echo "net.ipv4.conf.default.send_redirects = 0" >> /etc/sysctl.conf
fi
|
Disable Kernel Parameter for Sending ICMP Redirects for All Interfacesrule
To set the runtime status of the net.ipv4.conf.all.send_redirects kernel parameter,
run the following command:
$ sudo sysctl -w net.ipv4.conf.all.send_redirects=0
If this is not the system's default value, add the following line to /etc/sysctl.conf:
net.ipv4.conf.all.send_redirects = 0
identifiers:
CCE-27004-1, DISA FSO RHEL-06-000081 references:
CM-7, SC-5(1), 1551, Test attestation on 20121024 by DS Remediation script:#
# Set runtime for net.ipv4.conf.all.send_redirects
#
/sbin/sysctl -q -n -w net.ipv4.conf.all.send_redirects=0
#
# If net.ipv4.conf.all.send_redirects present in /etc/sysctl.conf, change value to "0"
# else, add "net.ipv4.conf.all.send_redirects = 0" to /etc/sysctl.conf
#
if grep --silent ^net.ipv4.conf.all.send_redirects /etc/sysctl.conf ; then
sed -i 's/^net.ipv4.conf.all.send_redirects.*/net.ipv4.conf.all.send_redirects = 0/g' /etc/sysctl.conf
else
echo -e "\n# Set net.ipv4.conf.all.send_redirects to 0 per security requirements" >> /etc/sysctl.conf
echo "net.ipv4.conf.all.send_redirects = 0" >> /etc/sysctl.conf
fi
|
Disable Kernel Parameter for IP Forwardingrule
To set the runtime status of the net.ipv4.ip_forward kernel parameter,
run the following command:
$ sudo sysctl -w net.ipv4.ip_forward=0
If this is not the system's default value, add the following line to /etc/sysctl.conf:
net.ipv4.ip_forward = 0
identifiers:
CCE-26866-4, DISA FSO RHEL-06-000082 references:
CM-7, SC-5, 366, Test attestation on 20121024 by DS |
Network Related Kernel Runtime Parameters for Hosts and RoutersgroupCertain kernel parameters should be set for systems which are
acting as either hosts or routers to improve the system's ability defend
against certain types of IPv4 protocol attacks. |
contains 12 rules |
Disable Kernel Parameter for Accepting Source-Routed Packets for All Interfacesrule
To set the runtime status of the net.ipv4.conf.all.accept_source_route kernel parameter,
run the following command:
$ sudo sysctl -w net.ipv4.conf.all.accept_source_route=0
If this is not the system's default value, add the following line to /etc/sysctl.conf:
net.ipv4.conf.all.accept_source_route = 0
identifiers:
CCE-27037-1, DISA FSO RHEL-06-000083 references:
CM-7, SC-5, 1551, Test attestation on 20121024 by DS Remediation script:#
# Set runtime for net.ipv4.conf.all.accept_source_route
#
/sbin/sysctl -q -n -w net.ipv4.conf.all.accept_source_route=0
#
# If net.ipv4.conf.all.accept_source_route present in /etc/sysctl.conf, change value to "0"
# else, add "net.ipv4.conf.all.accept_source_route = 0" to /etc/sysctl.conf
#
if grep --silent ^net.ipv4.conf.all.accept_source_route /etc/sysctl.conf ; then
sed -i 's/^net.ipv4.conf.all.accept_source_route.*/net.ipv4.conf.all.accept_source_route = 0/g' /etc/sysctl.conf
else
echo -e "\n# Set net.ipv4.conf.all.accept_source_route to 0 per security requirements" >> /etc/sysctl.conf
echo "net.ipv4.conf.all.accept_source_route = 0" >> /etc/sysctl.conf
fi
|
Disable Kernel Parameter for Accepting ICMP Redirects for All Interfacesrule
To set the runtime status of the net.ipv4.conf.all.accept_redirects kernel parameter,
run the following command:
$ sudo sysctl -w net.ipv4.conf.all.accept_redirects=0
If this is not the system's default value, add the following line to /etc/sysctl.conf:
net.ipv4.conf.all.accept_redirects = 0
identifiers:
CCE-27027-2, DISA FSO RHEL-06-000084 references:
CM-7, SC-5, 1503, 1551, Test attestation on 20121024 by DS Remediation script:#
# Set runtime for net.ipv4.conf.all.accept_redirects
#
/sbin/sysctl -q -n -w net.ipv4.conf.all.accept_redirects=0
#
# If net.ipv4.conf.all.accept_redirects present in /etc/sysctl.conf, change value to "0"
# else, add "net.ipv4.conf.all.accept_redirects = 0" to /etc/sysctl.conf
#
if grep --silent ^net.ipv4.conf.all.accept_redirects /etc/sysctl.conf ; then
sed -i 's/^net.ipv4.conf.all.accept_redirects.*/net.ipv4.conf.all.accept_redirects = 0/g' /etc/sysctl.conf
else
echo -e "\n# Set net.ipv4.conf.all.accept_redirects to 0 per security requirements" >> /etc/sysctl.conf
echo "net.ipv4.conf.all.accept_redirects = 0" >> /etc/sysctl.conf
fi
|
Disable Kernel Parameter for Accepting Secure Redirects for All Interfacesrule
To set the runtime status of the net.ipv4.conf.all.secure_redirects kernel parameter,
run the following command:
$ sudo sysctl -w net.ipv4.conf.all.secure_redirects=0
If this is not the system's default value, add the following line to /etc/sysctl.conf:
net.ipv4.conf.all.secure_redirects = 0
identifiers:
CCE-26854-0, DISA FSO RHEL-06-000086 references:
AC-4, CM-7, SC-5, 1503, 1551, Test attestation on 20121024 by DS Remediation script:#
# Set runtime for net.ipv4.conf.all.secure_redirects
#
/sbin/sysctl -q -n -w net.ipv4.conf.all.secure_redirects=0
#
# If net.ipv4.conf.all.secure_redirects present in /etc/sysctl.conf, change value to "0"
# else, add "net.ipv4.conf.all.secure_redirects = 0" to /etc/sysctl.conf
#
if grep --silent ^net.ipv4.conf.all.secure_redirects /etc/sysctl.conf ; then
sed -i 's/^net.ipv4.conf.all.secure_redirects.*/net.ipv4.conf.all.secure_redirects = 0/g' /etc/sysctl.conf
else
echo -e "\n# Set net.ipv4.conf.all.secure_redirects to 0 per security requirements" >> /etc/sysctl.conf
echo "net.ipv4.conf.all.secure_redirects = 0" >> /etc/sysctl.conf
fi
|
Enable Kernel Parameter to Log Martian Packetsrule
To set the runtime status of the net.ipv4.conf.all.log_martians kernel parameter,
run the following command:
$ sudo sysctl -w net.ipv4.conf.all.log_martians=1
If this is not the system's default value, add the following line to /etc/sysctl.conf:
net.ipv4.conf.all.log_martians = 1
identifiers:
CCE-27066-0, DISA FSO RHEL-06-000088 references:
AC-3(10), CM-7, SC-5(3), 126, Test attestation on 20121024 by DS Remediation script:#
# Set runtime for net.ipv4.conf.all.log_martians
#
/sbin/sysctl -q -n -w net.ipv4.conf.all.log_martians=1
#
# If net.ipv4.conf.all.log_martians present in /etc/sysctl.conf, change value to "1"
# else, add "net.ipv4.conf.all.log_martians = 1" to /etc/sysctl.conf
#
if grep --silent ^net.ipv4.conf.all.log_martians /etc/sysctl.conf ; then
sed -i 's/^net.ipv4.conf.all.log_martians.*/net.ipv4.conf.all.log_martians = 1/g' /etc/sysctl.conf
else
echo -e "\n# Set net.ipv4.conf.all.log_martians to 1 per security requirements" >> /etc/sysctl.conf
echo "net.ipv4.conf.all.log_martians = 1" >> /etc/sysctl.conf
fi
|
Disable Kernel Parameter for Accepting Source-Routed Packets By Defaultrule
To set the runtime status of the net.ipv4.conf.default.accept_source_route kernel parameter,
run the following command:
$ sudo sysctl -w net.ipv4.conf.default.accept_source_route=0
If this is not the system's default value, add the following line to /etc/sysctl.conf:
net.ipv4.conf.default.accept_source_route = 0
identifiers:
CCE-26983-7, DISA FSO RHEL-06-000089 references:
AC-4, CM-7, SC-5, SC-7, 1551, Test attestation on 20121024 by DS Remediation script:#
# Set runtime for net.ipv4.conf.default.accept_source_route
#
/sbin/sysctl -q -n -w net.ipv4.conf.default.accept_source_route=0
#
# If net.ipv4.conf.default.accept_source_route present in /etc/sysctl.conf, change value to "0"
# else, add "net.ipv4.conf.default.accept_source_route = 0" to /etc/sysctl.conf
#
if grep --silent ^net.ipv4.conf.default.accept_source_route /etc/sysctl.conf ; then
sed -i 's/^net.ipv4.conf.default.accept_source_route.*/net.ipv4.conf.default.accept_source_route = 0/g' /etc/sysctl.conf
else
echo -e "\n# Set net.ipv4.conf.default.accept_source_route to 0 per security requirements" >> /etc/sysctl.conf
echo "net.ipv4.conf.default.accept_source_route = 0" >> /etc/sysctl.conf
fi
|
Disable Kernel Parameter for Accepting ICMP Redirects By Defaultrule
To set the runtime status of the net.ipv4.conf.default.accept_redirects kernel parameter,
run the following command:
$ sudo sysctl -w net.ipv4.conf.default.accept_redirects=0
If this is not the system's default value, add the following line to /etc/sysctl.conf:
net.ipv4.conf.default.accept_redirects = 0
identifiers:
CCE-27015-7, DISA FSO RHEL-06-000091 references:
AC-4, CM-7, SC-5, SC-7, 1551, Test attestation on 20121024 by DS Remediation script:#
# Set runtime for net.ipv4.conf.default.accept_redirects
#
/sbin/sysctl -q -n -w net.ipv4.conf.default.accept_redirects=0
#
# If net.ipv4.conf.default.accept_redirects present in /etc/sysctl.conf, change value to "0"
# else, add "net.ipv4.conf.default.accept_redirects = 0" to /etc/sysctl.conf
#
if grep --silent ^net.ipv4.conf.default.accept_redirects /etc/sysctl.conf ; then
sed -i 's/^net.ipv4.conf.default.accept_redirects.*/net.ipv4.conf.default.accept_redirects = 0/g' /etc/sysctl.conf
else
echo -e "\n# Set net.ipv4.conf.default.accept_redirects to 0 per security requirements" >> /etc/sysctl.conf
echo "net.ipv4.conf.default.accept_redirects = 0" >> /etc/sysctl.conf
fi
|
Disable Kernel Parameter for Accepting Secure Redirects By Defaultrule
To set the runtime status of the net.ipv4.conf.default.secure_redirects kernel parameter,
run the following command:
$ sudo sysctl -w net.ipv4.conf.default.secure_redirects=0
If this is not the system's default value, add the following line to /etc/sysctl.conf:
net.ipv4.conf.default.secure_redirects = 0
identifiers:
CCE-26831-8, DISA FSO RHEL-06-000090 references:
AC-4, CM-7, SC-5, SC-7, 1551, Test attestation on 20121024 by DS Remediation script:#
# Set runtime for net.ipv4.conf.default.secure_redirects
#
/sbin/sysctl -q -n -w net.ipv4.conf.default.secure_redirects=0
#
# If net.ipv4.conf.default.secure_redirects present in /etc/sysctl.conf, change value to "0"
# else, add "net.ipv4.conf.default.secure_redirects = 0" to /etc/sysctl.conf
#
if grep --silent ^net.ipv4.conf.default.secure_redirects /etc/sysctl.conf ; then
sed -i 's/^net.ipv4.conf.default.secure_redirects.*/net.ipv4.conf.default.secure_redirects = 0/g' /etc/sysctl.conf
else
echo -e "\n# Set net.ipv4.conf.default.secure_redirects to 0 per security requirements" >> /etc/sysctl.conf
echo "net.ipv4.conf.default.secure_redirects = 0" >> /etc/sysctl.conf
fi
|
Enable Kernel Parameter to Ignore ICMP Broadcast Echo Requestsrule
To set the runtime status of the net.ipv4.icmp_echo_ignore_broadcasts kernel parameter,
run the following command:
$ sudo sysctl -w net.ipv4.icmp_echo_ignore_broadcasts=1
If this is not the system's default value, add the following line to /etc/sysctl.conf:
net.ipv4.icmp_echo_ignore_broadcasts = 1
identifiers:
CCE-26883-9, DISA FSO RHEL-06-000092 references:
CM-7, SC-5, 1551, Test attestation on 20121024 by DS Remediation script:#
# Set runtime for net.ipv4.icmp_echo_ignore_broadcasts
#
/sbin/sysctl -q -n -w net.ipv4.icmp_echo_ignore_broadcasts=1
#
# If net.ipv4.icmp_echo_ignore_broadcasts present in /etc/sysctl.conf, change value to "1"
# else, add "net.ipv4.icmp_echo_ignore_broadcasts = 1" to /etc/sysctl.conf
#
if grep --silent ^net.ipv4.icmp_echo_ignore_broadcasts /etc/sysctl.conf ; then
sed -i 's/^net.ipv4.icmp_echo_ignore_broadcasts.*/net.ipv4.icmp_echo_ignore_broadcasts = 1/g' /etc/sysctl.conf
else
echo -e "\n# Set net.ipv4.icmp_echo_ignore_broadcasts to 1 per security requirements" >> /etc/sysctl.conf
echo "net.ipv4.icmp_echo_ignore_broadcasts = 1" >> /etc/sysctl.conf
fi
|
Enable Kernel Parameter to Ignore Bogus ICMP Error Responsesrule
To set the runtime status of the net.ipv4.icmp_ignore_bogus_error_responses kernel parameter,
run the following command:
$ sudo sysctl -w net.ipv4.icmp_ignore_bogus_error_responses=1
If this is not the system's default value, add the following line to /etc/sysctl.conf:
net.ipv4.icmp_ignore_bogus_error_responses = 1
identifiers:
CCE-26993-6, DISA FSO RHEL-06-000093 references:
CM-7, SC-5, Test attestation on 20121024 by DS Remediation script:#
# Set runtime for net.ipv4.icmp_ignore_bogus_error_responses
#
/sbin/sysctl -q -n -w net.ipv4.icmp_ignore_bogus_error_responses=1
#
# If net.ipv4.icmp_ignore_bogus_error_responses present in /etc/sysctl.conf, change value to "1"
# else, add "net.ipv4.icmp_ignore_bogus_error_responses = 1" to /etc/sysctl.conf
#
if grep --silent ^net.ipv4.icmp_ignore_bogus_error_responses /etc/sysctl.conf ; then
sed -i 's/^net.ipv4.icmp_ignore_bogus_error_responses.*/net.ipv4.icmp_ignore_bogus_error_responses = 1/g' /etc/sysctl.conf
else
echo -e "\n# Set net.ipv4.icmp_ignore_bogus_error_responses to 1 per security requirements" >> /etc/sysctl.conf
echo "net.ipv4.icmp_ignore_bogus_error_responses = 1" >> /etc/sysctl.conf
fi
|
Enable Kernel Parameter to Use TCP Syncookiesrule
To set the runtime status of the net.ipv4.tcp_syncookies kernel parameter,
run the following command:
$ sudo sysctl -w net.ipv4.tcp_syncookies=1
If this is not the system's default value, add the following line to /etc/sysctl.conf:
net.ipv4.tcp_syncookies = 1
identifiers:
CCE-27053-8, DISA FSO RHEL-06-000095 references:
AC-4, SC-5(2), SC-5(3), 1092, 1095, Test attestation on 20121024 by DS Remediation script:#
# Set runtime for net.ipv4.tcp_syncookies
#
/sbin/sysctl -q -n -w net.ipv4.tcp_syncookies=1
#
# If net.ipv4.tcp_syncookies present in /etc/sysctl.conf, change value to "1"
# else, add "net.ipv4.tcp_syncookies = 1" to /etc/sysctl.conf
#
if grep --silent ^net.ipv4.tcp_syncookies /etc/sysctl.conf ; then
sed -i 's/^net.ipv4.tcp_syncookies.*/net.ipv4.tcp_syncookies = 1/g' /etc/sysctl.conf
else
echo -e "\n# Set net.ipv4.tcp_syncookies to 1 per security requirements" >> /etc/sysctl.conf
echo "net.ipv4.tcp_syncookies = 1" >> /etc/sysctl.conf
fi
|
Enable Kernel Parameter to Use Reverse Path Filtering for All Interfacesrule
To set the runtime status of the net.ipv4.conf.all.rp_filter kernel parameter,
run the following command:
$ sudo sysctl -w net.ipv4.conf.all.rp_filter=1
If this is not the system's default value, add the following line to /etc/sysctl.conf:
net.ipv4.conf.all.rp_filter = 1
identifiers:
CCE-26979-5, DISA FSO RHEL-06-000096 references:
AC-4, SC-5, SC-7, 1551, Test attestation on 20121024 by DS Remediation script:#
# Set runtime for net.ipv4.conf.all.rp_filter
#
/sbin/sysctl -q -n -w net.ipv4.conf.all.rp_filter=1
#
# If net.ipv4.conf.all.rp_filter present in /etc/sysctl.conf, change value to "1"
# else, add "net.ipv4.conf.all.rp_filter = 1" to /etc/sysctl.conf
#
if grep --silent ^net.ipv4.conf.all.rp_filter /etc/sysctl.conf ; then
sed -i 's/^net.ipv4.conf.all.rp_filter.*/net.ipv4.conf.all.rp_filter = 1/g' /etc/sysctl.conf
else
echo -e "\n# Set net.ipv4.conf.all.rp_filter to 1 per security requirements" >> /etc/sysctl.conf
echo "net.ipv4.conf.all.rp_filter = 1" >> /etc/sysctl.conf
fi
|
Enable Kernel Parameter to Use Reverse Path Filtering by Defaultrule
To set the runtime status of the net.ipv4.conf.default.rp_filter kernel parameter,
run the following command:
$ sudo sysctl -w net.ipv4.conf.default.rp_filter=1
If this is not the system's default value, add the following line to /etc/sysctl.conf:
net.ipv4.conf.default.rp_filter = 1
identifiers:
CCE-26915-9, DISA FSO RHEL-06-000097 references:
AC-4, SC-5, SC-7, Test attestation on 20121024 by DS Remediation script:#
# Set runtime for net.ipv4.conf.default.rp_filter
#
/sbin/sysctl -q -n -w net.ipv4.conf.default.rp_filter=1
#
# If net.ipv4.conf.default.rp_filter present in /etc/sysctl.conf, change value to "1"
# else, add "net.ipv4.conf.default.rp_filter = 1" to /etc/sysctl.conf
#
if grep --silent ^net.ipv4.conf.default.rp_filter /etc/sysctl.conf ; then
sed -i 's/^net.ipv4.conf.default.rp_filter.*/net.ipv4.conf.default.rp_filter = 1/g' /etc/sysctl.conf
else
echo -e "\n# Set net.ipv4.conf.default.rp_filter to 1 per security requirements" >> /etc/sysctl.conf
echo "net.ipv4.conf.default.rp_filter = 1" >> /etc/sysctl.conf
fi
|
Wireless NetworkinggroupWireless networking, such as 802.11
(WiFi) and Bluetooth, can present a security risk to sensitive or
classified systems and networks. Wireless networking hardware is
much more likely to be included in laptop or portable systems than
in desktops or servers.
Removal of hardware provides the greatest assurance that the wireless
capability remains disabled. Acquisition policies often include provisions to
prevent the purchase of equipment that will be used in sensitive spaces and
includes wireless capabilities. If it is impractical to remove the wireless
hardware, and policy permits the device to enter sensitive spaces as long
as wireless is disabled, efforts should instead focus on disabling wireless capability
via software. |
contains 2 rules |
Disable Wireless Through Software ConfigurationgroupIf it is impossible to remove the wireless hardware
from the device in question, disable as much of it as possible
through software. The following methods can disable software
support for wireless networking, but note that these methods do not
prevent malicious software or careless users from re-activating the
devices. |
contains 2 rules |
Disable WiFi or Bluetooth in BIOSruleSome systems that include built-in wireless support offer the
ability to disable the device through the BIOS. This is system-specific;
consult your hardware manual or explore the BIOS setup during
boot. identifiers:
CCE-26878-9 references:
AC-18(a), AC-18(d), AC-18(3), CM-7, 85 |
Deactivate Wireless Network InterfacesruleDeactivating wireless network interfaces should prevent
normal usage of the wireless capability.
First, identify the interfaces available with the command:
$ ifconfig -a
Additionally, the following command may be used to
determine whether wireless support is included for a
particular interface, though this may not always be a clear
indicator:
$ iwconfig
After identifying any wireless interfaces (which may have
names like wlan0, ath0, wifi0, em1 or
eth0), deactivate the interface with the command:
$ sudo ifdown interface
These changes will only last until the next reboot. To
disable the interface for future boots, remove the appropriate
interface file from /etc/sysconfig/network-scripts:
$ sudo rm /etc/sysconfig/network-scripts/ifcfg-interface
identifiers:
CCE-27057-9 references:
AC-18(a), AC-18(d), AC-18(3), CM-7, 85, Test attestation on 20121025 by DS |
IPv6groupThe system includes support for Internet Protocol
version 6. A major and often-mentioned improvement over IPv4 is its
enormous increase in the number of available addresses. Another
important feature is its support for automatic configuration of
many network settings. |
contains 3 rules |
Disable Support for IPv6 Unless Neededgroup
Despite configuration that suggests support for IPv6 has
been disabled, link-local IPv6 address auto-configuration occurs
even when only an IPv4 address is assigned. The only way to
effectively prevent execution of the IPv6 networking stack is to
instruct the system not to activate the IPv6 kernel module.
|
contains 1 rule |
Disable Interface Usage of IPv6ruleTo disable interface usage of IPv6, add or correct the following lines in /etc/sysconfig/network:
NETWORKING_IPV6=no
IPV6INIT=no
identifiers:
CCE-27161-9 |
Configure IPv6 Settings if NecessarygroupA major feature of IPv6 is the extent to which systems
implementing it can automatically configure their networking
devices using information from the network. From a security
perspective, manually configuring important configuration
information is preferable to accepting it from the network
in an unauthenticated fashion. |
contains 2 rules |
Disable Automatic ConfigurationgroupDisable the system's acceptance of router
advertisements and redirects by adding or correcting the following
line in /etc/sysconfig/network (note that this does not disable
sending router solicitations):
IPV6_AUTOCONF=no
|
contains 2 rules |
Disable Accepting IPv6 Router Advertisementsrule
To set the runtime status of the net.ipv6.conf.default.accept_ra kernel parameter,
run the following command:
$ sudo sysctl -w net.ipv6.conf.default.accept_ra=0
If this is not the system's default value, add the following line to /etc/sysctl.conf:
net.ipv6.conf.default.accept_ra = 0
identifiers:
CCE-27164-3 references:
CM-7 Remediation script:#
# Set runtime for net.ipv6.conf.default.accept_ra
#
/sbin/sysctl -q -n -w net.ipv6.conf.default.accept_ra=0
#
# If net.ipv6.conf.default.accept_ra present in /etc/sysctl.conf, change value to "0"
# else, add "net.ipv6.conf.default.accept_ra = 0" to /etc/sysctl.conf
#
if grep --silent ^net.ipv6.conf.default.accept_ra /etc/sysctl.conf ; then
sed -i 's/^net.ipv6.conf.default.accept_ra.*/net.ipv6.conf.default.accept_ra = 0/g' /etc/sysctl.conf
else
echo -e "\n# Set net.ipv6.conf.default.accept_ra to 0 per security requirements" >> /etc/sysctl.conf
echo "net.ipv6.conf.default.accept_ra = 0" >> /etc/sysctl.conf
fi
|
Disable Accepting IPv6 Redirectsrule
To set the runtime status of the net.ipv6.conf.default.accept_redirects kernel parameter,
run the following command:
$ sudo sysctl -w net.ipv6.conf.default.accept_redirects=0
If this is not the system's default value, add the following line to /etc/sysctl.conf:
net.ipv6.conf.default.accept_redirects = 0
identifiers:
CCE-27166-8, DISA FSO RHEL-06-000099 references:
CM-7, 1551 Remediation script:#
# Set runtime for net.ipv6.conf.default.accept_redirects
#
/sbin/sysctl -q -n -w net.ipv6.conf.default.accept_redirects=0
#
# If net.ipv6.conf.default.accept_redirects present in /etc/sysctl.conf, change value to "0"
# else, add "net.ipv6.conf.default.accept_redirects = 0" to /etc/sysctl.conf
#
if grep --silent ^net.ipv6.conf.default.accept_redirects /etc/sysctl.conf ; then
sed -i 's/^net.ipv6.conf.default.accept_redirects.*/net.ipv6.conf.default.accept_redirects = 0/g' /etc/sysctl.conf
else
echo -e "\n# Set net.ipv6.conf.default.accept_redirects to 0 per security requirements" >> /etc/sysctl.conf
echo "net.ipv6.conf.default.accept_redirects = 0" >> /etc/sysctl.conf
fi
|
iptables and ip6tablesgroupA host-based firewall called netfilter is included as
part of the Linux kernel distributed with the system. It is
activated by default. This firewall is controlled by the program
iptables, and the entire capability is frequently referred to by
this name. An analogous program called ip6tables handles filtering
for IPv6.
Unlike TCP Wrappers, which depends on the network server
program to support and respect the rules written, netfilter
filtering occurs at the kernel level, before a program can even
process the data from the network packet. As such, any program on
the system is affected by the rules written.
This section provides basic information about strengthening
the iptables and ip6tables configurations included with the system.
For more complete information that may allow the construction of a
sophisticated ruleset tailored to your environment, please consult
the references at the end of this section. |
contains 2 rules |
Inspect and Activate Default RulesgroupView the currently-enforced iptables rules by running
the command:
$ sudo iptables -nL --line-numbers
The command is analogous for ip6tables.
If the firewall does not appear to be active (i.e., no rules
appear), activate it and ensure that it starts at boot by issuing
the following commands (and analogously for ip6tables):
$ sudo service iptables restart
The default iptables rules are:
Chain INPUT (policy ACCEPT)
num target prot opt source destination
1 ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
2 ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0
3 ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
4 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22
5 REJECT all -- 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited
Chain FORWARD (policy ACCEPT)
num target prot opt source destination
1 REJECT all -- 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited
Chain OUTPUT (policy ACCEPT)
num target prot opt source destination
The ip6tables default rules are essentially the same. |
contains 2 rules |
Verify ip6tables Enabled if Using IPv6rule
The ip6tables service can be enabled with the following command:
$ sudo chkconfig --level 2345 ip6tables on
identifiers:
CCE-27006-6, DISA FSO RHEL-06-000103 references:
AC-4, CA-3(c), CM-7, 32, 66, 1115, 1118, 1092, 1117, 1098, 1100, 1097, 1414, Test attestation on 20121024 by DS Remediation script:#
# Enable ip6tables for all run levels
#
/sbin/chkconfig --level 0123456 ip6tables on
#
# Start ip6tables if not currently running
#
/sbin/service ip6tables start
|
Verify iptables Enabledrule
The iptables service can be enabled with the following command:
$ sudo chkconfig --level 2345 iptables on
identifiers:
CCE-27018-1, DISA FSO RHEL-06-000117 references:
AC-4, CA-3(c), CM-7, 32, 66, 1115, 1118, 1092, 1117, 1098, 1100, 1097, 1414, Test attestation on 20121024 by DS Remediation script:#
# Enable iptables for all run levels
#
/sbin/chkconfig --level 0123456 iptables on
#
# Start iptables if not currently running
#
/sbin/service iptables start
|
Uncommon Network ProtocolsgroupThe system includes support for several network
protocols which are not commonly used. Although security vulnerabilities
in kernel networking code are not frequently
discovered, the consequences can be dramatic. Ensuring uncommon
network protocols are disabled reduces the system's risk to attacks
targeted at its implementation of those protocols. |
contains 4 rules |
Disable DCCP Supportrule
The Datagram Congestion Control Protocol (DCCP) is a
relatively new transport layer protocol, designed to support
streaming media and telephony.
To configure the system to prevent the dccp
kernel module from being loaded, add the following line to a file in the directory /etc/modprobe.d:
install dccp /bin/true
identifiers:
CCE-26448-1, DISA FSO RHEL-06-000124 references:
CM-7, 382, Test attestation on 20121024 by DS Remediation script:echo "install dccp /bin/true" > /etc/modprobe.d/dccp.conf
|
Disable SCTP Supportrule
The Stream Control Transmission Protocol (SCTP) is a
transport layer protocol, designed to support the idea of
message-oriented communication, with several streams of messages
within one connection.
To configure the system to prevent the sctp
kernel module from being loaded, add the following line to a file in the directory /etc/modprobe.d:
install sctp /bin/true
identifiers:
CCE-26410-1, DISA FSO RHEL-06-000125 references:
CM-7, 382, Test attestation on 20121024 by DS Remediation script:echo "install sctp /bin/true" > /etc/modprobe.d/sctp.conf
|
Disable RDS Supportrule
The Reliable Datagram Sockets (RDS) protocol is a transport
layer protocol designed to provide reliable high- bandwidth,
low-latency communications between nodes in a cluster.
To configure the system to prevent the rds
kernel module from being loaded, add the following line to a file in the directory /etc/modprobe.d:
install rds /bin/true
identifiers:
CCE-26239-4, DISA FSO RHEL-06-000126 references:
CM-7, 382, Test attestation on 20121024 by DS Remediation script:echo "install rds /bin/true" > /etc/modprobe.d/rds.conf
|
Disable TIPC Supportrule
The Transparent Inter-Process Communication (TIPC) protocol
is designed to provide communications between nodes in a
cluster.
To configure the system to prevent the tipc
kernel module from being loaded, add the following line to a file in the directory /etc/modprobe.d:
install tipc /bin/true
identifiers:
CCE-26696-5, DISA FSO RHEL-06-000127 references:
CM-7, 382, Test attestation on 20121024 by DS Remediation script:echo "install tipc /bin/true" > /etc/modprobe.d/tipc.conf
|
Configure SysloggroupThe syslog service has been the default Unix logging mechanism for
many years. It has a number of downsides, including inconsistent log format,
lack of authentication for received messages, and lack of authentication,
encryption, or reliable transport for messages sent over a network. However,
due to its long history, syslog is a de facto standard which is supported by
almost all Unix applications.
In Red Hat Enterprise Linux 6, rsyslog has replaced ksyslogd as the
syslog daemon of choice, and it includes some additional security features
such as reliable, connection-oriented (i.e. TCP) transmission of logs, the
option to log to database formats, and the encryption of log data en route to
a central logging server.
This section discusses how to configure rsyslog for
best effect, and how to use tools provided with the system to maintain and
monitor logs. |
contains 6 rules |
Ensure Proper Configuration of Log Filesgroup
The file /etc/rsyslog.conf controls where log message are written.
These are controlled by lines called rules, which consist of a
selector and an action.
These rules are often customized depending on the role of the system, the
requirements of the environment, and whatever may enable
the administrator to most effectively make use of log data.
The default rules in Red Hat Enterprise Linux 6 are:
*.info;mail.none;authpriv.none;cron.none /var/log/messages
authpriv.* /var/log/secure
mail.* -/var/log/maillog
cron.* /var/log/cron
*.emerg *
uucp,news.crit /var/log/spooler
local7.* /var/log/boot.log
See the man page rsyslog.conf(5) for more information.
Note that the rsyslog daemon can be configured to use a timestamp format that
some log processing programs may not understand. If this occurs,
edit the file /etc/rsyslog.conf and add or edit the following line:
$ ActionFileDefaultTemplate RSYSLOG_TraditionalFileFormat
|
contains 1 rule |
Ensure System Log Files Have Correct PermissionsruleThe file permissions for all log files written by
rsyslog should be set to 600, or more restrictive.
These log files are determined by the second part of each Rule line in
/etc/rsyslog.conf and typically all appear in /var/log.
For each log file LOGFILE referenced in /etc/rsyslog.conf,
run the following command to inspect the file's permissions:
$ ls -l LOGFILE
If the permissions are not 600 or more restrictive,
run the following command to correct this:
$ sudo chmod 0600 LOGFILE
identifiers:
CCE-27190-8, DISA FSO RHEL-06-000135 references:
SI-11, 1314, Test attestation on 20121024 by DS |
Rsyslog Logs Sent To Remote Hostgroup
If system logs are to be useful in detecting malicious
activities, it is necessary to send logs to a remote server. An
intruder who has compromised the root account on a machine may
delete the log entries which indicate that the system was attacked
before they are seen by an administrator.
However, it is recommended that logs be stored on the local
host in addition to being sent to the loghost, especially if
rsyslog has been configured to use the UDP protocol to send
messages over a network. UDP does not guarantee reliable delivery,
and moderately busy sites will lose log messages occasionally,
especially in periods of high traffic which may be the result of an
attack. In addition, remote rsyslog messages are not
authenticated in any way by default, so it is easy for an attacker to
introduce spurious messages to the central log server. Also, some
problems cause loss of network connectivity, which will prevent the
sending of messages to the central server. For all of these reasons, it is
better to store log messages both centrally and on each host, so
that they can be correlated if necessary. |
contains 1 rule |
Ensure Logs Sent To Remote Hostrule
To configure rsyslog to send logs to a remote log server,
open /etc/rsyslog.conf and read and understand the last section of the file,
which describes the multiple directives necessary to activate remote
logging.
Along with these other directives, the system can be configured
to forward its logs to a particular log server by
adding or correcting one of the following lines,
substituting loghost.example.com appropriately.
The choice of protocol depends on the environment of the system;
although TCP and RELP provide more reliable message delivery,
they may not be supported in all environments.
To use UDP for log message delivery:
*.* @loghost.example.com
To use TCP for log message delivery:
*.* @@loghost.example.com
To use RELP for log message delivery:
*.* :omrelp:loghost.example.com
identifiers:
CCE-26801-1, DISA FSO RHEL-06-000136 references:
AU-3(2), AU-9, 1348, 136 |
Configure rsyslogd to Accept Remote Messages If Acting as a Log Servergroup
By default, rsyslog does not listen over the network
for log messages. If needed, modules can be enabled to allow
the rsyslog daemon to receive messages from other systems and for the system
thus to act as a log server.
If the machine is not a log server, then lines concerning these modules
should remain commented out.
|
contains 1 rule |
Ensure rsyslog Does Not Accept Remote Messages Unless Acting As Log ServerruleThe rsyslog daemon should not accept remote messages
unless the system acts as a log server.
To ensure that it is not listening on the network, ensure the following lines are
not found in /etc/rsyslog.conf:
$ModLoad imtcp
$InputTCPServerRun port
$ModLoad imudp
$UDPServerRun port
$ModLoad imrelp
$InputRELPServerRun port
identifiers:
CCE-26803-7 references:
AU-9(2), AC-4 |
Ensure All Logs are Rotated by logrotategroupEdit the file /etc/logrotate.d/syslog. Find the first
line, which should look like this (wrapped for clarity):
/var/log/messages /var/log/secure /var/log/maillog /var/log/spooler \
/var/log/boot.log /var/log/cron {
Edit this line so that it contains a one-space-separated
listing of each log file referenced in /etc/rsyslog.conf.
All logs in use on a system must be rotated regularly, or the
log files will consume disk space over time, eventually interfering
with system operation. The file /etc/logrotate.d/syslog is the
configuration file used by the logrotate program to maintain all
log files written by syslog. By default, it rotates logs weekly and
stores four archival copies of each log. These settings can be
modified by editing /etc/logrotate.conf, but the defaults are
sufficient for purposes of this guide.
Note that logrotate is run nightly by the cron job
/etc/cron.daily/logrotate. If particularly active logs need to be
rotated more often than once a day, some other mechanism must be
used. |
contains 1 rule |
Ensure Logrotate Runs PeriodicallyruleThe logrotate utility allows for the automatic rotation of
log files. The frequency of rotation is specified in /etc/logrotate.conf,
which triggers a cron task. To configure logrotate to run daily, add or correct
the following line in /etc/logrotate.conf:
# rotate log files frequency
daily
identifiers:
CCE-27014-0, DISA FSO RHEL-06-000138 references:
AU-9, 366 |
Ensure rsyslog is Installedrule
Rsyslog is installed by default.
The rsyslog package can be installed with the following command:
$ sudo yum install rsyslog
identifiers:
CCE-26809-4 references:
AU-9(2), 1311, 1312, Test attestation on 20121024 by DS Remediation script:yum -y install rsyslog
|
Enable rsyslog ServiceruleThe rsyslog service provides syslog-style logging by default on Red Hat Enterprise Linux 6.
The rsyslog service can be enabled with the following command:
$ sudo chkconfig --level 2345 rsyslog on
identifiers:
CCE-26807-8 references:
AU-12, 1557, 1312, 1311, Test attestation on 20121024 by DS Remediation script:#
# Enable rsyslog for all run levels
#
/sbin/chkconfig --level 0123456 rsyslog on
#
# Start rsyslog if not currently running
#
/sbin/service rsyslog start
|
System Accounting with auditdgroupThe audit service provides substantial capabilities
for recording system activities. By default, the service audits about
SELinux AVC denials and certain types of security-relevant events
such as system logins, account modifications, and authentication
events performed by programs such as sudo.
Under its default configuration, auditd has modest disk space
requirements, and should not noticeably impact system performance.
Government networks often have substantial auditing
requirements and auditd can be configured to meet these
requirements.
Examining some example audit records demonstrates how the Linux audit system
satisfies common requirements.
The following example from Fedora Documentation available at
http://docs.fedoraproject.org/en-US/Fedora/13/html/Security-Enhanced_Linux/sect-Security-Enhanced_Linux-Fixing_Problems-Raw_Audit_Messages.html
shows the substantial amount of information captured in a
two typical "raw" audit messages, followed by a breakdown of the most important
fields. In this example the message is SELinux-related and reports an AVC
denial (and the associated system call) that occurred when the Apache HTTP
Server attempted to access the /var/www/html/file1 file (labeled with
the samba_share_t type):
type=AVC msg=audit(1226874073.147:96): avc: denied { getattr } for pid=2465 comm="httpd"
path="/var/www/html/file1" dev=dm-0 ino=284133 scontext=unconfined_u:system_r:httpd_t:s0
tcontext=unconfined_u:object_r:samba_share_t:s0 tclass=file
type=SYSCALL msg=audit(1226874073.147:96): arch=40000003 syscall=196 success=no exit=-13
a0=b98df198 a1=bfec85dc a2=54dff4 a3=2008171 items=0 ppid=2463 pid=2465 auid=502 uid=48
gid=48 euid=48 suid=48 fsuid=48 egid=48 sgid=48 fsgid=48 tty=(none) ses=6 comm="httpd"
exe="/usr/sbin/httpd" subj=unconfined_u:system_r:httpd_t:s0 key=(null)
msg=audit(1226874073.147:96)The number in parentheses is the unformatted time stamp (Epoch time)
for the event, which can be converted to standard time by using the
date command.
{ getattr }The item in braces indicates the permission that was denied. getattr
indicates the source process was trying to read the target file's status information.
This occurs before reading files. This action is denied due to the file being
accessed having the wrong label. Commonly seen permissions include getattr,
read, and write.comm="httpd"The executable that launched the process. The full path of the executable is
found in the exe= section of the system call (SYSCALL) message,
which in this case, is exe="/usr/sbin/httpd".
path="/var/www/html/file1"The path to the object (target) the process attempted to access.
scontext="unconfined_u:system_r:httpd_t:s0"The SELinux context of the process that attempted the denied action. In
this case, it is the SELinux context of the Apache HTTP Server, which is running
in the httpd_t domain.
tcontext="unconfined_u:object_r:samba_share_t:s0"The SELinux context of the object (target) the process attempted to access.
In this case, it is the SELinux context of file1. Note: the samba_share_t
type is not accessible to processes running in the httpd_t domain. From the system call (SYSCALL) message, two items are of interest:
success=no: indicates whether the denial (AVC) was enforced or not.
success=no indicates the system call was not successful (SELinux denied
access). success=yes indicates the system call was successful - this can
be seen for permissive domains or unconfined domains, such as initrc_t
and kernel_t.
exe="/usr/sbin/httpd": the full path to the executable that launched
the process, which in this case, is exe="/usr/sbin/httpd".
|
contains 23 rules |
Configure auditd Data Retentiongroup
The audit system writes data to /var/log/audit/audit.log. By default,
auditd rotates 5 logs by size (6MB), retaining a maximum of 30MB of
data in total, and refuses to write entries when the disk is too
full. This minimizes the risk of audit data filling its partition
and impacting other services. This also minimizes the risk of the audit
daemon temporarily disabling the system if it cannot write audit log (which
it can be configured to do).
For a busy
system or a system which is thoroughly auditing system activity, the default settings
for data retention may be
insufficient. The log file size needed will depend heavily on what types
of events are being audited. First configure auditing to log all the events of
interest. Then monitor the log size manually for awhile to determine what file
size will allow you to keep the required data for the correct time period.
Using a dedicated partition for /var/log/audit prevents the
auditd logs from disrupting system functionality if they fill, and,
more importantly, prevents other activity in /var from filling the
partition and stopping the audit trail. (The audit logs are size-limited and
therefore unlikely to grow without bound unless configured to do so.) Some
machines may have requirements that no actions occur which cannot be audited.
If this is the case, then auditd can be configured to halt the machine
if it runs out of space. Note: Since older logs are rotated,
configuring auditd this way does not prevent older logs from being
rotated away before they can be viewed.
If your system is configured to halt when logging cannot be performed, make
sure this can never happen under normal circumstances! Ensure that
/var/log/audit is on its own partition, and that this partition is
larger than the maximum amount of data auditd will retain
normally.
references:
AU-11, 138 |
contains 5 rules |
Configure auditd Max Log File SizeruleDetermine the amount of audit data (in megabytes)
which should be retained in each log file. Edit the file
/etc/audit/auditd.conf. Add or modify the following line, substituting
the correct value of 6 for STOREMB:
max_log_file = STOREMB
Set the value to 6 (MB) or higher for general-purpose systems.
Larger values, of course,
support retention of even more audit data. identifiers:
CCE-27550-3, DISA FSO RHEL-06-000160 references:
AU-1(b), AU-11, IR-5, Test attestation on 20121024 by DS |
Configure auditd max_log_file_action Upon Reaching Maximum Log Sizerule The default action to take when the logs reach their maximum size
is to rotate the log files, discarding the oldest one. To configure the action taken
by auditd, add or correct the line in /etc/audit/auditd.conf:
max_log_file_action = ACTION
Possible values for ACTION are described in the auditd.conf man
page. These include:
ignoresyslogsuspendrotatekeep_logs
Set the ACTION to rotate to ensure log rotation
occurs. This is the default. The setting is case-insensitive.
identifiers:
CCE-27237-7, DISA FSO RHEL-06-000161 references:
AU-1(b), AU-4, AU-11, IR-5, Test attestation on 20121024 by DS |
Configure auditd space_left Action on Low Disk SpaceruleThe auditd service can be configured to take an action
when disk space starts to run low.
Edit the file /etc/audit/auditd.conf. Modify the following line,
substituting ACTION appropriately:
space_left_action = ACTION
Possible values for ACTION are described in the auditd.conf man page.
These include:
ignoresyslogemailexecsuspendsinglehalt
Set this to email (instead of the default,
which is suspend) as it is more likely to get prompt attention. Acceptable values
also include suspend, single, and halt.
identifiers:
CCE-27238-5, DISA FSO RHEL-06-000005 references:
AU-1(b), AU-4, AU-5(b), IR-5, 140, 143, Test attestation on 20121024 by DS Remediation script:var_auditd_space_left_action="email"
#
# If space_left_action present in /etc/audit/auditd.conf, change value
# to var_auditd_space_left_action, else
# add "space_left_action = $var_auditd_space_left_action" to /etc/audit/auditd.conf
#
if grep --silent ^space_left_action /etc/audit/auditd.conf ; then
sed -i 's/^space_left_action.*/space_left_action = '"$var_auditd_space_left_action"'/g' /etc/audit/auditd.conf
else
echo -e "\n# Set space_left_action to $var_auditd_space_left_action per security requirements" >> /etc/audit/auditd.conf
echo "space_left_action = $var_auditd_space_left_action" >> /etc/audit/auditd.conf
fi
|
Configure auditd admin_space_left Action on Low Disk SpaceruleThe auditd service can be configured to take an action
when disk space is running low but prior to running out of space completely.
Edit the file /etc/audit/auditd.conf. Add or modify the following line,
substituting ACTION appropriately:
admin_space_left_action = ACTION
Set this value to single to cause the system to switch to single-user
mode for corrective action. Acceptable values also include suspend and
halt. For certain systems, the need for availability
outweighs the need to log all actions, and a different setting should be
determined. Details regarding all possible values for ACTION are described in the
auditd.conf man page.
identifiers:
CCE-27239-3 references:
AU-1(b), AU-4, AU-5(b), IR-5, 140, 1343, Test attestation on 20121024 by DS Remediation script:var_auditd_admin_space_left_action="single"
grep -q ^admin_space_left_action /etc/audit/auditd.conf && \
sed -i "s/admin_space_left_action.*/admin_space_left_action = $var_auditd_admin_space_left_action/g" /etc/audit/auditd.conf
if ! [ $? -eq 0 ]; then
echo "admin_space_left_action = $var_auditd_admin_space_left_action" >> /etc/audit/auditd.conf
fi
|
Configure auditd mail_acct Action on Low Disk SpaceruleThe auditd service can be configured to send email to
a designated account in certain situations. Add or correct the following line
in /etc/audit/auditd.conf to ensure that administrators are notified
via email for those situations:
action_mail_acct = root
identifiers:
CCE-27241-9, DISA FSO RHEL-06-000313 references:
AU-1(b), AU-4, AU-5(a), IR-5, 139, 144 |
Configure auditd Rules for Comprehensive AuditinggroupThe auditd program can perform comprehensive
monitoring of system activity. This section describes recommended
configuration settings for comprehensive auditing, but a full
description of the auditing system's capabilities is beyond the
scope of this guide. The mailing list linux-audit@redhat.com exists
to facilitate community discussion of the auditing system.
The audit subsystem supports extensive collection of events, including:
Tracing of arbitrary system calls (identified by name or number)
on entry or exit.Filtering by PID, UID, call success, system call argument (with
some limitations), etc.Monitoring of specific files for modifications to the file's
contents or metadata.
Auditing rules at startup are controlled by the file /etc/audit/audit.rules.
Add rules to it to meet the auditing requirements for your organization.
Each line in /etc/audit/audit.rules represents a series of arguments
that can be passed to auditctl and can be individually tested
during runtime. See documentation in /usr/share/doc/audit-VERSION and
in the related man pages for more details.
If copying any example audit rulesets from /usr/share/doc/audit-VERSION,
be sure to comment out the
lines containing arch= which are not appropriate for your system's
architecture. Then review and understand the following rules,
ensuring rules are activated as needed for the appropriate
architecture.
After reviewing all the rules, reading the following sections, and
editing as needed, the new rules can be activated as follows:
$ sudo service auditd restart
|
contains 16 rules |
Records Events that Modify Date and Time InformationgroupArbitrary changes to the system time can be used to obfuscate
nefarious activities in log files, as well as to confuse network services that
are highly dependent upon an accurate system time. All changes to the system
time should be audited. |
contains 4 rules |
Record attempts to alter time through adjtimexruleOn a 32-bit system, add the following to /etc/audit/audit.rules:
# audit_time_rules
-a always,exit -F arch=b32 -S adjtimex -k audit_time_rules
On a 64-bit system, add the following to /etc/audit/audit.rules:
# audit_time_rules
-a always,exit -F arch=b64 -S adjtimex -k audit_time_rules
The -k option allows for the specification of a key in string form that can
be used for better reporting capability through ausearch and aureport.
Multiple system calls can be defined on the same line to save space if
desired, but is not required. See an example of multiple combined syscalls:
-a always,exit -F arch=b64 -S adjtimex -S settimeofday -S clock_settime
-k audit_time_rules
identifiers:
CCE-26242-8, DISA FSO RHEL-06-000165 references:
AC-3(10), AU-1(b), AU-2(a), AU-2(c), AU-2(d), AU-12(a), AU-12(c), IR-5, 1487, 169 Remediation script:
# audit.rules file to operate at
AUDIT_RULES_FILE="/etc/audit/audit.rules"
# General form / skeleton of an audit rule to search for
BASE_SEARCH_RULE='-a always,exit .* -k audit_time_rules'
# System calls group to search for
SYSCALL_GROUP="time"
# Retrieve hardware architecture of the underlying system
[ $(getconf LONG_BIT) = "32" ] && ARCHS=("b32") || ARCHS=("b32" "b64")
# Perform the remediation depending on the system's architecture:
# * on 32 bit system, operate just at '-F arch=b32' audit rules
# * on 64 bit system, operate at both '-F arch=b32' & '-F arch=b64' audit rules
for ARCH in ${ARCHS[@]}
do
# Create expected audit rule form for particular system call & architecture
if [ ${ARCH} = "b32" ]
then
# stime system call is known at 32-bit arch (see e.g "$ ausyscall i386 stime" 's output)
# so append it to the list of time group system calls to be audited
EXPECTED_RULE="-a always,exit -F arch=b32 -S adjtimex -S settimeofday -S stime -k audit_time_rules"
else
# stime system call isn't known at 64-bit arch (see "$ ausyscall x86_64 stime" 's output)
# therefore don't add it to the list of time group system calls to be audited
EXPECTED_RULE="-a always,exit -F arch=b64 -S adjtimex -S settimeofday -k audit_time_rules"
fi
# Indicator that we want to append $EXPECTED_RULE for key & arch into
# audit.rules by default
APPEND_EXPECTED_RULE=0
# From all the existing /etc/audit.rule definitions select those, which:
# * follow the common audit rule form ($BASE_SEARCH_RULE above)
# * meet the hardware architecture requirement, and
# * are current $SYSCALL_GROUP specific
IFS=$'\n' EXISTING_KEY_ARCH_RULES=($(sed -e "/${BASE_SEARCH_RULE}/!d" -e "/${ARCH}/!d" -e "/${SYSCALL_GROUP}/!d" ${AUDIT_RULES_FILE}))
# Process found rules case by case
for RULE in ${EXISTING_KEY_ARCH_RULES[@]}
do
# Found rule is for same arch & syscall group, but differs slightly (in count of -S arguments)
if [ ${RULE} != ${EXPECTED_RULE} ]
then
# If so, isolate just '-S syscall' substring of that rule
RULE_SYSCALLS=$(echo ${RULE} | grep -o -P '(-S \w+ )+')
# Check if list of '-S syscall' arguments of that rule is a subset
# '-S syscall' list from the expected form ($EXPECTED_RULE)
if [ $(echo ${EXPECTED_RULE} | grep -- ${RULE_SYSCALLS}) ]
then
# If so, this audit rule is covered when we append expected rule
# later & therefore the rule can be deleted.
#
# Thus delete the rule from both - the audit.rules file and
# our $EXISTING_KEY_ARCH_RULES array
sed -i -e "/${RULE}/d" ${AUDIT_RULES_FILE}
EXISTING_KEY_ARCH_RULES=(${EXISTING_KEY_ARCH_RULES[@]//${RULE}/})
else
# Rule isn't covered by $EXPECTED_RULE - in other words it besides
# adjtimex, settimeofday, or stime -S arguments contains also -S argument
# for other time group system call (-S clock_adjtime for example).
# Example: '-S adjtimex -S clock_adjtime'
#
# Therefore:
# * delete the original rule for arch & key from audit.rules
# (original '-S adjtimex -S clock_adjtime' rule would be deleted)
# * delete $SYSCALL_GROUP -S arguments from the rule,
# but keep those not from this $SYSCALL_GROUP
# (original '-S adjtimex -S clock_adjtime' would become '-S clock_adjtime')
# * append the modified (filtered) rule again into audit.rules
# if the same rule not already present
# (new rule for same arch & key with '-S clock_adjtime' would be appended
# if not present yet)
sed -i -e "/${RULE}/d" ${AUDIT_RULES_FILE}
if [ ${ARCH} = "b32" ]
then
# On 32-bit arch drop ' -S (adjtimex|settimeofday|stime)' from the rule's
# system call list
NEW_SYSCALLS_FOR_RULE=$(echo ${RULE_SYSCALLS} | sed -r -e "s/[\s]*-S (adjtimex|settimeofday|stime)//g")
else
# On 64-bit arch drop ' -S (adjtimex|settimeofday)' from the rule's
# system call list ('stime' call isn't known, see "$ ausyscall .." examples above)
NEW_SYSCALLS_FOR_RULE=$(echo ${RULE_SYSCALLS} | sed -r -e "s/[\s]*-S (adjtimex|settimeofday)//g")
fi
# Update the list of system calls for new rule to contain those from new syscalls list
UPDATED_RULE=$(echo ${RULE} | sed "s/${RULE_SYSCALLS}/${NEW_SYSCALLS_FOR_RULE}/g")
# Squeeze repeated whitespace characters in rule definition (if any) into one
UPDATED_RULE=$(echo ${UPDATED_RULE} | tr -s '[:space:]')
# Insert updated rule into /etc/audit/audit.rules only in case it's not
# present yet to prevent duplicate same rules
if [ ! $(grep -- ${UPDATED_RULE} ${AUDIT_RULES_FILE}) ]
then
echo ${UPDATED_RULE} >> ${AUDIT_RULES_FILE}
fi
fi
else
# /etc/audit/audit.rules already contains the expected rule form for this
# architecture & key => don't insert it second time
APPEND_EXPECTED_RULE=1
fi
done
# We deleted all rules that were subset of the expected one for this arch & key.
# Also isolated rules containing system calls not from this system calls group.
# Now append the expected rule if it's not present in audit.rules yet
if [[ ${APPEND_EXPECTED_RULE} -eq "0" ]]
then
echo ${EXPECTED_RULE} >> ${AUDIT_RULES_FILE}
fi
done
|
Record attempts to alter time through settimeofdayruleOn a 32-bit system, add the following to /etc/audit/audit.rules:
# audit_time_rules
-a always,exit -F arch=b32 -S settimeofday -k audit_time_rules
On a 64-bit system, add the following to /etc/audit/audit.rules:
# audit_time_rules
-a always,exit -F arch=b64 -S settimeofday -k audit_time_rules
The -k option allows for the specification of a key in string form that can
be used for better reporting capability through ausearch and aureport.
Multiple system calls can be defined on the same line to save space if
desired, but is not required. See an example of multiple combined syscalls:
-a always,exit -F arch=b64 -S adjtimex -S settimeofday -S clock_settime
-k audit_time_rules
identifiers:
CCE-27203-9, DISA FSO RHEL-06-000167 references:
AC-3(10), AU-1(b), AU-2(a), AU-2(c), AU-2(d), AU-12(a), AU-12(c), IR-5, 1487, 169 Remediation script:
# audit.rules file to operate at
AUDIT_RULES_FILE="/etc/audit/audit.rules"
# General form / skeleton of an audit rule to search for
BASE_SEARCH_RULE='-a always,exit .* -k audit_time_rules'
# System calls group to search for
SYSCALL_GROUP="time"
# Retrieve hardware architecture of the underlying system
[ $(getconf LONG_BIT) = "32" ] && ARCHS=("b32") || ARCHS=("b32" "b64")
# Perform the remediation depending on the system's architecture:
# * on 32 bit system, operate just at '-F arch=b32' audit rules
# * on 64 bit system, operate at both '-F arch=b32' & '-F arch=b64' audit rules
for ARCH in ${ARCHS[@]}
do
# Create expected audit rule form for particular system call & architecture
if [ ${ARCH} = "b32" ]
then
# stime system call is known at 32-bit arch (see e.g "$ ausyscall i386 stime" 's output)
# so append it to the list of time group system calls to be audited
EXPECTED_RULE="-a always,exit -F arch=b32 -S adjtimex -S settimeofday -S stime -k audit_time_rules"
else
# stime system call isn't known at 64-bit arch (see "$ ausyscall x86_64 stime" 's output)
# therefore don't add it to the list of time group system calls to be audited
EXPECTED_RULE="-a always,exit -F arch=b64 -S adjtimex -S settimeofday -k audit_time_rules"
fi
# Indicator that we want to append $EXPECTED_RULE for key & arch into
# audit.rules by default
APPEND_EXPECTED_RULE=0
# From all the existing /etc/audit.rule definitions select those, which:
# * follow the common audit rule form ($BASE_SEARCH_RULE above)
# * meet the hardware architecture requirement, and
# * are current $SYSCALL_GROUP specific
IFS=$'\n' EXISTING_KEY_ARCH_RULES=($(sed -e "/${BASE_SEARCH_RULE}/!d" -e "/${ARCH}/!d" -e "/${SYSCALL_GROUP}/!d" ${AUDIT_RULES_FILE}))
# Process found rules case by case
for RULE in ${EXISTING_KEY_ARCH_RULES[@]}
do
# Found rule is for same arch & syscall group, but differs slightly (in count of -S arguments)
if [ ${RULE} != ${EXPECTED_RULE} ]
then
# If so, isolate just '-S syscall' substring of that rule
RULE_SYSCALLS=$(echo ${RULE} | grep -o -P '(-S \w+ )+')
# Check if list of '-S syscall' arguments of that rule is a subset
# '-S syscall' list from the expected form ($EXPECTED_RULE)
if [ $(echo ${EXPECTED_RULE} | grep -- ${RULE_SYSCALLS}) ]
then
# If so, this audit rule is covered when we append expected rule
# later & therefore the rule can be deleted.
#
# Thus delete the rule from both - the audit.rules file and
# our $EXISTING_KEY_ARCH_RULES array
sed -i -e "/${RULE}/d" ${AUDIT_RULES_FILE}
EXISTING_KEY_ARCH_RULES=(${EXISTING_KEY_ARCH_RULES[@]//${RULE}/})
else
# Rule isn't covered by $EXPECTED_RULE - in other words it besides
# adjtimex, settimeofday, or stime -S arguments contains also -S argument
# for other time group system call (-S clock_adjtime for example).
# Example: '-S adjtimex -S clock_adjtime'
#
# Therefore:
# * delete the original rule for arch & key from audit.rules
# (original '-S adjtimex -S clock_adjtime' rule would be deleted)
# * delete $SYSCALL_GROUP -S arguments from the rule,
# but keep those not from this $SYSCALL_GROUP
# (original '-S adjtimex -S clock_adjtime' would become '-S clock_adjtime')
# * append the modified (filtered) rule again into audit.rules
# if the same rule not already present
# (new rule for same arch & key with '-S clock_adjtime' would be appended
# if not present yet)
sed -i -e "/${RULE}/d" ${AUDIT_RULES_FILE}
if [ ${ARCH} = "b32" ]
then
# On 32-bit arch drop ' -S (adjtimex|settimeofday|stime)' from the rule's
# system call list
NEW_SYSCALLS_FOR_RULE=$(echo ${RULE_SYSCALLS} | sed -r -e "s/[\s]*-S (adjtimex|settimeofday|stime)//g")
else
# On 64-bit arch drop ' -S (adjtimex|settimeofday)' from the rule's
# system call list ('stime' call isn't known, see "$ ausyscall .." examples above)
NEW_SYSCALLS_FOR_RULE=$(echo ${RULE_SYSCALLS} | sed -r -e "s/[\s]*-S (adjtimex|settimeofday)//g")
fi
# Update the list of system calls for new rule to contain those from new syscalls list
UPDATED_RULE=$(echo ${RULE} | sed "s/${RULE_SYSCALLS}/${NEW_SYSCALLS_FOR_RULE}/g")
# Squeeze repeated whitespace characters in rule definition (if any) into one
UPDATED_RULE=$(echo ${UPDATED_RULE} | tr -s '[:space:]')
# Insert updated rule into /etc/audit/audit.rules only in case it's not
# present yet to prevent duplicate same rules
if [ ! $(grep -- ${UPDATED_RULE} ${AUDIT_RULES_FILE}) ]
then
echo ${UPDATED_RULE} >> ${AUDIT_RULES_FILE}
fi
fi
else
# /etc/audit/audit.rules already contains the expected rule form for this
# architecture & key => don't insert it second time
APPEND_EXPECTED_RULE=1
fi
done
# We deleted all rules that were subset of the expected one for this arch & key.
# Also isolated rules containing system calls not from this system calls group.
# Now append the expected rule if it's not present in audit.rules yet
if [[ ${APPEND_EXPECTED_RULE} -eq "0" ]]
then
echo ${EXPECTED_RULE} >> ${AUDIT_RULES_FILE}
fi
done
|
Record Attempts to Alter Time Through stimeruleOn a 32-bit system, add the following to /etc/audit/audit.rules:
# audit_time_rules
-a always,exit -F arch=b32 -S stime -k audit_time_rules
On a 64-bit system, the "-S stime" is not necessary. The -k option allows for
the specification of a key in string form that can be used for better
reporting capability through ausearch and aureport. Multiple system calls
can be defined on the same line to save space if desired, but is not required.
See an example of multiple combined syscalls:
-a always,exit -F arch=b64 -S adjtimex -S settimeofday -S clock_settime
-k audit_time_rules
identifiers:
CCE-27169-2, DISA FSO RHEL-06-000169 references:
AC-3(10), AU-1(b), AU-2(a), AU-2(c), AU-2(d), AU-12(a), AU-12(c), IR-5, 1487, 169 Remediation script:
# audit.rules file to operate at
AUDIT_RULES_FILE="/etc/audit/audit.rules"
# General form / skeleton of an audit rule to search for
BASE_SEARCH_RULE='-a always,exit .* -k audit_time_rules'
# System calls group to search for
SYSCALL_GROUP="time"
# Retrieve hardware architecture of the underlying system
[ $(getconf LONG_BIT) = "32" ] && ARCHS=("b32") || ARCHS=("b32" "b64")
# Perform the remediation depending on the system's architecture:
# * on 32 bit system, operate just at '-F arch=b32' audit rules
# * on 64 bit system, operate at both '-F arch=b32' & '-F arch=b64' audit rules
for ARCH in ${ARCHS[@]}
do
# Create expected audit rule form for particular system call & architecture
if [ ${ARCH} = "b32" ]
then
# stime system call is known at 32-bit arch (see e.g "$ ausyscall i386 stime" 's output)
# so append it to the list of time group system calls to be audited
EXPECTED_RULE="-a always,exit -F arch=b32 -S adjtimex -S settimeofday -S stime -k audit_time_rules"
else
# stime system call isn't known at 64-bit arch (see "$ ausyscall x86_64 stime" 's output)
# therefore don't add it to the list of time group system calls to be audited
EXPECTED_RULE="-a always,exit -F arch=b64 -S adjtimex -S settimeofday -k audit_time_rules"
fi
# Indicator that we want to append $EXPECTED_RULE for key & arch into
# audit.rules by default
APPEND_EXPECTED_RULE=0
# From all the existing /etc/audit.rule definitions select those, which:
# * follow the common audit rule form ($BASE_SEARCH_RULE above)
# * meet the hardware architecture requirement, and
# * are current $SYSCALL_GROUP specific
IFS=$'\n' EXISTING_KEY_ARCH_RULES=($(sed -e "/${BASE_SEARCH_RULE}/!d" -e "/${ARCH}/!d" -e "/${SYSCALL_GROUP}/!d" ${AUDIT_RULES_FILE}))
# Process found rules case by case
for RULE in ${EXISTING_KEY_ARCH_RULES[@]}
do
# Found rule is for same arch & syscall group, but differs slightly (in count of -S arguments)
if [ ${RULE} != ${EXPECTED_RULE} ]
then
# If so, isolate just '-S syscall' substring of that rule
RULE_SYSCALLS=$(echo ${RULE} | grep -o -P '(-S \w+ )+')
# Check if list of '-S syscall' arguments of that rule is a subset
# '-S syscall' list from the expected form ($EXPECTED_RULE)
if [ $(echo ${EXPECTED_RULE} | grep -- ${RULE_SYSCALLS}) ]
then
# If so, this audit rule is covered when we append expected rule
# later & therefore the rule can be deleted.
#
# Thus delete the rule from both - the audit.rules file and
# our $EXISTING_KEY_ARCH_RULES array
sed -i -e "/${RULE}/d" ${AUDIT_RULES_FILE}
EXISTING_KEY_ARCH_RULES=(${EXISTING_KEY_ARCH_RULES[@]//${RULE}/})
else
# Rule isn't covered by $EXPECTED_RULE - in other words it besides
# adjtimex, settimeofday, or stime -S arguments contains also -S argument
# for other time group system call (-S clock_adjtime for example).
# Example: '-S adjtimex -S clock_adjtime'
#
# Therefore:
# * delete the original rule for arch & key from audit.rules
# (original '-S adjtimex -S clock_adjtime' rule would be deleted)
# * delete $SYSCALL_GROUP -S arguments from the rule,
# but keep those not from this $SYSCALL_GROUP
# (original '-S adjtimex -S clock_adjtime' would become '-S clock_adjtime')
# * append the modified (filtered) rule again into audit.rules
# if the same rule not already present
# (new rule for same arch & key with '-S clock_adjtime' would be appended
# if not present yet)
sed -i -e "/${RULE}/d" ${AUDIT_RULES_FILE}
if [ ${ARCH} = "b32" ]
then
# On 32-bit arch drop ' -S (adjtimex|settimeofday|stime)' from the rule's
# system call list
NEW_SYSCALLS_FOR_RULE=$(echo ${RULE_SYSCALLS} | sed -r -e "s/[\s]*-S (adjtimex|settimeofday|stime)//g")
else
# On 64-bit arch drop ' -S (adjtimex|settimeofday)' from the rule's
# system call list ('stime' call isn't known, see "$ ausyscall .." examples above)
NEW_SYSCALLS_FOR_RULE=$(echo ${RULE_SYSCALLS} | sed -r -e "s/[\s]*-S (adjtimex|settimeofday)//g")
fi
# Update the list of system calls for new rule to contain those from new syscalls list
UPDATED_RULE=$(echo ${RULE} | sed "s/${RULE_SYSCALLS}/${NEW_SYSCALLS_FOR_RULE}/g")
# Squeeze repeated whitespace characters in rule definition (if any) into one
UPDATED_RULE=$(echo ${UPDATED_RULE} | tr -s '[:space:]')
# Insert updated rule into /etc/audit/audit.rules only in case it's not
# present yet to prevent duplicate same rules
if [ ! $(grep -- ${UPDATED_RULE} ${AUDIT_RULES_FILE}) ]
then
echo ${UPDATED_RULE} >> ${AUDIT_RULES_FILE}
fi
fi
else
# /etc/audit/audit.rules already contains the expected rule form for this
# architecture & key => don't insert it second time
APPEND_EXPECTED_RULE=1
fi
done
# We deleted all rules that were subset of the expected one for this arch & key.
# Also isolated rules containing system calls not from this system calls group.
# Now append the expected rule if it's not present in audit.rules yet
if [[ ${APPEND_EXPECTED_RULE} -eq "0" ]]
then
echo ${EXPECTED_RULE} >> ${AUDIT_RULES_FILE}
fi
done
|
Record Attempts to Alter the localtime FileruleAdd the following to /etc/audit/audit.rules:
-w /etc/localtime -p wa -k audit_time_rules
The -k option allows for the specification of a key in string form that can
be used for better reporting capability through ausearch and aureport and
should always be used.
identifiers:
CCE-27172-6, DISA FSO RHEL-06-000173 references:
AC-3(10), AU-1(b), AU-2(a), AU-2(c), AU-2(d), AU-12(a), AU-12(c), IR-5, 1487, 169 Remediation script:
# Include source function library.
. /usr/share/scap-security-guide/remediation_functions
# Perform the remediation
fix_audit_watch_rule "auditctl" "/etc/localtime" "wa" "audit_time_rules"
|
Record Events that Modify User/Group InformationruleAdd the following to /etc/audit/audit.rules, in order
to capture events that modify account changes:
# audit_rules_usergroup_modification
-w /etc/group -p wa -k audit_rules_usergroup_modification
-w /etc/passwd -p wa -k audit_rules_usergroup_modification
-w /etc/gshadow -p wa -k audit_rules_usergroup_modification
-w /etc/shadow -p wa -k audit_rules_usergroup_modification
-w /etc/security/opasswd -p wa -k audit_rules_usergroup_modification
identifiers:
CCE-26664-3, DISA FSO RHEL-06-000174 references:
AC-2(4), AC-3(10), AU-1(b), AU-2(a), AU-2(c), AU-2(d), AU-12(a), AU-12(c), IR-5, 18, 1403, 1404, 1405, 1684, 1683, 1685, 1686 Remediation script:
# Include source function library.
. /usr/share/scap-security-guide/remediation_functions
# Perform the remediation
fix_audit_watch_rule "auditctl" "/etc/group" "wa" "audit_rules_usergroup_modification"
fix_audit_watch_rule "auditctl" "/etc/passwd" "wa" "audit_rules_usergroup_modification"
fix_audit_watch_rule "auditctl" "/etc/gshadow" "wa" "audit_rules_usergroup_modification"
fix_audit_watch_rule "auditctl" "/etc/shadow" "wa" "audit_rules_usergroup_modification"
fix_audit_watch_rule "auditctl" "/etc/security/opasswd" "wa" "audit_rules_usergroup_modification"
|
Record Events that Modify the System's Network EnvironmentruleAdd the following to /etc/audit/audit.rules, setting
ARCH to either b32 or b64 as appropriate for your system:
# audit_rules_networkconfig_modification
-a always,exit -F arch=ARCH -S sethostname -S setdomainname -k audit_rules_networkconfig_modification
-w /etc/issue -p wa -k audit_rules_networkconfig_modification
-w /etc/issue.net -p wa -k audit_rules_networkconfig_modification
-w /etc/hosts -p wa -k audit_rules_networkconfig_modification
-w /etc/sysconfig/network -p wa -k audit_rules_networkconfig_modification
identifiers:
CCE-26648-6, DISA FSO RHEL-06-000182 references:
AC-3(10), AU-1(b), AU-2(a), AU-2(c), AU-2(d), AU-12(a), AU-12(c), IR-5 Remediation script:
# Include source function library.
. /usr/share/scap-security-guide/remediation_functions
# First perform the remediation of the syscall rule
# Retrieve hardware architecture of the underlying system
[ $(getconf LONG_BIT) = "32" ] && RULE_ARCHS=("b32") || RULE_ARCHS=("b32" "b64")
for ARCH in "${RULE_ARCHS[@]}"
do
PATTERN="-a always,exit -F arch=$ARCH -S .* -k *"
# Use escaped BRE regex to specify rule group
GROUP="set\(host\|domain\)name"
FULL_RULE="-a always,exit -F arch=$ARCH -S sethostname -S setdomainname -k audit_rules_networkconfig_modification"
fix_audit_syscall_rule "auditctl" "$PATTERN" "$GROUP" "$ARCH" "$FULL_RULE"
done
# Then perform the remediations for the watch rules
fix_audit_watch_rule "auditctl" "/etc/issue" "wa" "audit_rules_networkconfig_modification"
fix_audit_watch_rule "auditctl" "/etc/issue.net" "wa" "audit_rules_networkconfig_modification"
fix_audit_watch_rule "auditctl" "/etc/hosts" "wa" "audit_rules_networkconfig_modification"
fix_audit_watch_rule "auditctl" "/etc/sysconfig/network" "wa" "audit_rules_networkconfig_modification"
|
Record Events that Modify the System's Mandatory Access ControlsruleAdd the following to /etc/audit/audit.rules:
-w /etc/selinux/ -p wa -k MAC-policy
identifiers:
CCE-26657-7, DISA FSO RHEL-06-000183 references:
AC-3(10), AU-1(b), AU-2(a), AU-2(c), AU-2(d), AU-12(a), AU-12(c), IR-5 Remediation script:
# Include source function library.
. /usr/share/scap-security-guide/remediation_functions
# Perform the remediation
fix_audit_watch_rule "auditctl" "/etc/selinux/" "wa" "MAC-policy"
|
Record Attempts to Alter Login and Logout Eventsrule
The audit system already collects login info for all users and root. To watch for attempted manual edits of
files involved in storing login events, add the following to /etc/audit/audit.rules:
-w /var/log/faillog -p wa -k logins
-w /var/log/lastlog -p wa -k logins
identifiers:
CCE-26691-6 references:
AC-3(10), AU-1(b), AU-12(a), AU-12(c), IR-5 |
Record Attempts to Alter Process and Session Initiation Informationrule The audit system already collects process information for all
users and root. To watch for attempted manual edits of files involved in
storing such process information, add the following to
/etc/audit/audit.rules:
-w /var/run/utmp -p wa -k session
-w /var/log/btmp -p wa -k session
-w /var/log/wtmp -p wa -k session
identifiers:
CCE-26610-6 references:
AC-3(10), AU-1(b), AU-2(a), AU-2(c), AU-2(d), AU-12(a), AU-12(c), IR-5 Remediation script:
# Include source function library.
. /usr/share/scap-security-guide/remediation_functions
# Perform the remediation
fix_audit_watch_rule "auditctl" "/var/run/utmp" "wa" "session"
fix_audit_watch_rule "auditctl" "/var/log/btmp" "wa" "session"
fix_audit_watch_rule "auditctl" "/var/log/wtmp" "wa" "session"
|
Ensure auditd Collects Unauthorized Access Attempts to Files (unsuccessful)ruleAt a minimum the audit system should collect
unauthorized file accesses for all users and root. Add the following
to /etc/audit/audit.rules:
-a always,exit -F arch=b32 -S creat -S open -S openat -S open_by_handle_at -S truncate -S ftruncate -F exit=-EACCES -F auid>=500 -F auid!=4294967295 -k access
-a always,exit -F arch=b32 -S creat -S open -S openat -S open_by_handle_at -S truncate -S ftruncate -F exit=-EPERM -F auid>=500 -F auid!=4294967295 -k access
If the system is 64 bit then also add the following:
-a always,exit -F arch=b64 -S creat -S open -S openat -S open_by_handle_at -S truncate -S ftruncate -F exit=-EACCES -F auid>=500 -F auid!=4294967295 -k access
-a always,exit -F arch=b64 -S creat -S open -S openat -S open_by_handle_at -S truncate -S ftruncate -F exit=-EPERM -F auid>=500 -F auid!=4294967295 -k access
identifiers:
CCE-26712-0, DISA FSO RHEL-06-000197 references:
AC-3(10), AU-1(b), AU-2(a), AU-2(c), AU-2(d), AU-12(a), AU-12(c), IR-5, 126 Remediation script:
# Include source function library.
. /usr/share/scap-security-guide/remediation_functions
# Perform the remediation of the syscall rule
# Retrieve hardware architecture of the underlying system
[ $(getconf LONG_BIT) = "32" ] && RULE_ARCHS=("b32") || RULE_ARCHS=("b32" "b64")
for ARCH in "${RULE_ARCHS[@]}"
do
# First fix the -EACCES requirement
PATTERN="-a always,exit -F arch=$ARCH -S .* -F exit=-EACCES -F auid>=500 -F auid!=4294967295 -k *"
# Use escaped BRE regex to specify rule group
GROUP="\(creat\|open\|truncate\)"
FULL_RULE="-a always,exit -F arch=$ARCH -S creat -S open -S openat -S open_by_handle_at -S truncate -S ftruncate -F exit=-EACCES -F auid>=500 -F auid!=4294967295 -k access"
fix_audit_syscall_rule "auditctl" "$PATTERN" "$GROUP" "$ARCH" "$FULL_RULE"
# Then fix the -EPERM requirement
PATTERN="-a always,exit -F arch=$ARCH -S .* -F exit=-EPERM -F auid>=500 -F auid!=4294967295 -k *"
# No need to change content of $GROUP variable - it's the same as for -EACCES case above
FULL_RULE="-a always,exit -F arch=$ARCH -S creat -S open -S openat -S open_by_handle_at -S truncate -S ftruncate -F exit=-EPERM -F auid>=500 -F auid!=4294967295 -k access"
fix_audit_syscall_rule "auditctl" "$PATTERN" "$GROUP" "$ARCH" "$FULL_RULE"
done
|
Ensure auditd Collects Information on the Use of Privileged CommandsruleAt a minimum the audit system should collect the
execution of privileged commands for all users and root.
To find the relevant setuid / setgid programs, run the following command
for each local partition PART:
$ sudo find PART -xdev -type f -perm -4000 -o -type f -perm -2000 2>/dev/null
Then, for each setuid / setgid program on the system, add a line of the
following form to /etc/audit/audit.rules, where
SETUID_PROG_PATH is the full path to each setuid / setgid program
in the list:
-a always,exit -F path=SETUID_PROG_PATH -F perm=x -F auid>=500 -F auid!=4294967295 -k privileged
identifiers:
CCE-26457-2, DISA FSO RHEL-06-000198 references:
AC-3(10)), AU-1(b), AU-2(a), AU-2(c), AU-2(d), AC-6(9), AU-12(a), AU-12(c), IR-5, 40, Test attestation on 20140703 by JL Remediation script:
readonly AUDIT_RULES='/etc/audit/audit.rules'
# Obtain the list of SUID/SGID binaries on the particular system into PRIVILEGED_BINARIES array
PRIVILEGED_BINARIES=($(find / -xdev -type f -perm -4000 -o -type f -perm -2000 2>/dev/null))
# Keep list of SUID/SGID binaries that have been already handled within some previous iteration
declare -a SBINARIES_TO_SKIP=()
# For each found binary from that list...
for SBINARY in ${PRIVILEGED_BINARIES[@]}
do
# Replace possible slash '/' character in SBINARY definition so we could use it in sed expressions below
SBINARY_ESC=${SBINARY//$'/'/$'\/'}
# Check if this SBINARY wasn't already handled in some of the previous iterations
if [[ $(sed -ne "/$SBINARY_ESC/p" <<< ${SBINARIES_TO_SKIP[@]}) ]]
then
# If so, don't process it second time & go to process next SBINARY
continue
fi
# Search existing audit.rule's content for match. Match criteria:
# * existing rule is for the same SUID/SGID binary we are currently processing (but
# can contain multiple -F path= elements covering multiple SUID/SGID binaries)
# * existing rule contains all arguments from expected rule form (though can contain
# them in arbitrary order)
BASE_SEARCH=$(sed -e "/-a always,exit/!d" -e "/-F path=${SBINARY_ESC}/!d" \
-e "/-F path=[^[:space:]]\+/!d" -e "/-F perm=.*/!d" \
-e "/-F auid>=500/!d" -e "/-F auid!=4294967295/!d" \
-e "/-k privileged/!d" $AUDIT_RULES)
# Define expected rule form for this binary
EXPECTED_RULE="-a always,exit -F path=${SBINARY} -F perm=x -F auid>=500 -F auid!=4294967295 -k privileged"
# Require execute access type to be set for existing audit rule
EXEC_ACCESS='x'
# Search existing audit.rules content for presence of rule pattern for this binary
if [[ $BASE_SEARCH ]]
then
# Current /etc/audit/audit.rules already contains rule for this binary =>
# Store the exact form of found rule for this binary for further processing
CONCRETE_RULE=$BASE_SEARCH
# Select all other SUID/SGID binaries possibly also present in the found rule
IFS=$'\n' HANDLED_SBINARIES=($(grep -o -e "-F path=[^[:space:]]\+" <<< $CONCRETE_RULE))
IFS=$' ' HANDLED_SBINARIES=(${HANDLED_SBINARIES[@]//-F path=/})
# Merge the list of such SUID/SGID binaries found in this iteration with global list ignoring duplicates
SBINARIES_TO_SKIP=($(for i in "${SBINARIES_TO_SKIP[@]}" "${HANDLED_SBINARIES[@]}"; do echo $i; done | sort -du))
# Separate CONCRETE_RULE into three sections using hash '#'
# sign as a delimiter around rule's permission section borders
CONCRETE_RULE=$(echo $CONCRETE_RULE | sed -n "s/\(.*\)\+\(-F perm=[rwax]\+\)\+/\1#\2#/p")
# Split CONCRETE_RULE into head, perm, and tail sections using hash '#' delimiter
IFS=$'#' read RULE_HEAD RULE_PERM RULE_TAIL <<< "$CONCRETE_RULE"
# Extract already present exact access type [r|w|x|a] from rule's permission section
ACCESS_TYPE=${RULE_PERM//-F perm=/}
# Verify current permission access type(s) for rule contain 'x' (execute) permission
if ! grep -q "$EXEC_ACCESS" <<< "$ACCESS_TYPE"
then
# If not, append the 'x' (execute) permission to the existing access type bits
ACCESS_TYPE="$ACCESS_TYPE$EXEC_ACCESS"
# Reconstruct the permissions section for the rule
NEW_RULE_PERM="-F perm=$ACCESS_TYPE"
# Update existing rule in /etc/audit/audit.rules with the new permission section
sed -i "s#${RULE_HEAD}\(.*\)${RULE_TAIL}#${RULE_HEAD}${NEW_RULE_PERM}${RULE_TAIL}#" $AUDIT_RULES
fi
else
# Current /etc/audit/audit.rules content doesn't contain expected rule for this
# SUID/SGID binary yet => append it
echo $EXPECTED_RULE >> $AUDIT_RULES
fi
done
|
Ensure auditd Collects Information on Exporting to Media (successful)ruleAt a minimum the audit system should collect media
exportation events for all users and root. Add the following to
/etc/audit/audit.rules, setting ARCH to either b32 or b64 as
appropriate for your system:
-a always,exit -F arch=ARCH -S mount -F auid>=500 -F auid!=4294967295 -k export
identifiers:
CCE-26573-6, DISA FSO RHEL-06-000199 references:
AC-3(10), AU-1(b), AU-2(a), AU-2(c), AU-2(d), AU-12(a), AU-12(c), IR-5, 126, Test attestation on 20121024 by DS Remediation script:
# Include source function library.
. /usr/share/scap-security-guide/remediation_functions
# Perform the remediation of the syscall rule
# Retrieve hardware architecture of the underlying system
[ $(getconf LONG_BIT) = "32" ] && RULE_ARCHS=("b32") || RULE_ARCHS=("b32" "b64")
for ARCH in "${RULE_ARCHS[@]}"
do
PATTERN="-a always,exit -F arch=$ARCH -S .* -F auid>=500 -F auid!=4294967295 -k *"
GROUP="mount"
FULL_RULE="-a always,exit -F arch=$ARCH -S mount -F auid>=500 -F auid!=4294967295 -k export"
fix_audit_syscall_rule "auditctl" "$PATTERN" "$GROUP" "$ARCH" "$FULL_RULE"
done
|
Ensure auditd Collects File Deletion Events by UserruleAt a minimum the audit system should collect file
deletion events for all users and root. Add the following to
/etc/audit/audit.rules, setting ARCH to either b32 or b64 as
appropriate for your system:
-a always,exit -F arch=ARCH -S rmdir -S unlink -S unlinkat -S rename -S renameat -F auid>=500 -F auid!=4294967295 -k delete
identifiers:
CCE-26651-0, DISA FSO RHEL-06-000200 references:
AC-3(10), AU-1(b), AU-2(a), AU-2(c), AU-2(d), AU-12(a), AU-12(c), IR-5, 126 Remediation script:
# Include source function library.
. /usr/share/scap-security-guide/remediation_functions
# Perform the remediation for the syscall rule
# Retrieve hardware architecture of the underlying system
[ $(getconf LONG_BIT) = "32" ] && RULE_ARCHS=("b32") || RULE_ARCHS=("b32" "b64")
for ARCH in ${RULE_ARCHS[@]}
do
PATTERN="-a always,exit -F arch=$ARCH -S .* -F auid>=500 -F auid!=4294967295 -k delete"
# Use escaped BRE regex to specify rule group
GROUP="\(rmdir\|unlink\|rename\)"
FULL_RULE="-a always,exit -F arch=$ARCH -S rmdir -S unlink -S unlinkat -S rename -S renameat -F auid>=500 -F auid!=4294967295 -k delete"
fix_audit_syscall_rule "auditctl" "$PATTERN" "$GROUP" "$ARCH" "$FULL_RULE"
done
|
Ensure auditd Collects System Administrator ActionsruleAt a minimum the audit system should collect
administrator actions for all users and root. Add the following to
/etc/audit/audit.rules:
-w /etc/sudoers -p wa -k actions
identifiers:
CCE-26662-7, DISA FSO RHEL-06-000201 references:
AC-2(7)(b), AC-3(10), AU-1(b), AU-2(a), AU-2(c), AU-2(d), AU-12(a), AU-12(c), IR-5, 126, Test attestation on 20121024 by DS Remediation script:
# Include source function library.
. /usr/share/scap-security-guide/remediation_functions
# Perform the remediation
fix_audit_watch_rule "auditctl" "/etc/sudoers" "wa" "actions"
|
Ensure auditd Collects Information on Kernel Module Loading and UnloadingruleAdd the following to /etc/audit/audit.rules in order
to capture kernel module loading and unloading events, setting ARCH to either b32 or b64 as appropriate for your system:
-w /sbin/insmod -p x -k modules
-w /sbin/rmmod -p x -k modules
-w /sbin/modprobe -p x -k modules
-a always,exit -F arch=ARCH -S init_module -S delete_module -k modules
identifiers:
CCE-26611-4, DISA FSO RHEL-06-000202 references:
AC-3(10), AU-1(b), AU-2(a), AU-2(c), AU-2(d), AU-12(a), AU-12(c), IR-5, 126 Remediation script:
# Include source function library.
. /usr/share/scap-security-guide/remediation_functions
# First perform the remediation of the syscall rule
# Retrieve hardware architecture of the underlying system
# Note: 32-bit kernel modules can't be loaded / unloaded on 64-bit kernel =>
# it's not required on a 64-bit system to check also for the presence
# of 32-bit's equivalent of the corresponding rule. Therefore for
# each system it's enought to check presence of system's native rule form.
[ $(getconf LONG_BIT) = "32" ] && RULE_ARCHS=("b32") || RULE_ARCHS=("b64")
for ARCH in "${RULE_ARCHS[@]}"
do
PATTERN="-a always,exit -F arch=$ARCH -S .* -k *"
# Use escaped BRE regex to specify rule group
GROUP="\(init\|delete\)_module"
FULL_RULE="-a always,exit -F arch=$ARCH -S init_module -S delete_module -k modules"
fix_audit_syscall_rule "auditctl" "$PATTERN" "$GROUP" "$ARCH" "$FULL_RULE"
done
# Then perform the remediations for the watch rules
fix_audit_watch_rule "auditctl" "/sbin/insmod" "x" "modules"
fix_audit_watch_rule "auditctl" "/sbin/rmmod" "x" "modules"
fix_audit_watch_rule "auditctl" "/sbin/modprobe" "x" "modules"
|
Make the auditd Configuration ImmutableruleAdd the following to /etc/audit/audit.rules in order
to make the configuration immutable:
-e 2
With this setting, a reboot will be required to change any
audit rules. identifiers:
CCE-26612-2 references:
AC-6, AU-1(b), AU-2(a), AU-2(c), AU-2(d), IR-5 Remediation script:
readonly AUDIT_RULES='/etc/audit/audit.rules'
# If '-e .*' setting present in audit.rules already, delete it since the
# auditctl(8) manual page instructs it should be the last rule in configuration
sed -i '/-e[[:space:]]\+.*/d' $AUDIT_RULES
# Append '-e 2' requirement at the end of audit.rules
echo '' >> $AUDIT_RULES
echo '# Set the audit.rules configuration immutable per security requirements' >> $AUDIT_RULES
echo '# Reboot is required to change audit rules once this setting is applied' >> $AUDIT_RULES
echo '-e 2' >> $AUDIT_RULES
|
Enable auditd ServiceruleThe auditd service is an essential userspace component of
the Linux Auditing System, as it is responsible for writing audit records to
disk.
The auditd service can be enabled with the following command:
$ sudo chkconfig --level 2345 auditd on
identifiers:
CCE-27058-7, DISA FSO RHEL-06-000145 references:
AC-17(1), AU-1(b), AU-10, AU-12(a), AU-12(c), IR-5, 347, 157, 172, 880, 1353, 1462, 1487, 1115, 1454, 067, 158, 831, 1190, 1312, 1263, 130, 120, 1589, Test attestation on 20121024 by DS Remediation script:#
# Enable auditd for all run levels
#
/sbin/chkconfig --level 0123456 auditd on
#
# Start auditd if not currently running
#
/sbin/service auditd start
|
Enable Auditing for Processes Which Start Prior to the Audit DaemonruleTo ensure all processes can be audited, even
those which start prior to the audit daemon, add the argument
audit=1 to the kernel line in /etc/grub.conf, in the manner below:
kernel /vmlinuz-version ro vga=ext root=/dev/VolGroup00/LogVol00 rhgb quiet audit=1
identifiers:
CCE-26785-6, DISA FSO RHEL-06-000525 references:
AC-17(1), AU-14(1), AU-1(b), AU-2(a), AU-2(c), AU-2(d), AU-10, IR-5, 1464, 130 Remediation script:/sbin/grubby --update-kernel=ALL --args="audit=1"
|
Servicesgroup
The best protection against vulnerable software is running less software. This section describes how to review
the software which Red Hat Enterprise Linux 6 installs on a system and disable software which is not needed. It
then enumerates the software packages installed on a default Red Hat Enterprise Linux 6 system and provides guidance about which
ones can be safely disabled.
Red Hat Enterprise Linux 6 provides a convenient minimal install option that essentially installs the bare necessities for a functional
system. When building Red Hat Enterprise Linux 6 servers, it is highly recommended to select the minimal packages and then build up
the system from there.
|
contains 34 rules |
Obsolete ServicesgroupThis section discusses a number of network-visible
services which have historically caused problems for system
security, and for which disabling or severely limiting the service
has been the best available guidance for some time. As a result of
this, many of these services are not installed as part of Red Hat Enterprise Linux 6
by default.
Organizations which are running these services should
switch to more secure equivalents as soon as possible.
If it remains absolutely necessary to run one of
these services for legacy reasons, care should be taken to restrict
the service as much as possible, for instance by configuring host
firewall software such as iptables to restrict access to the
vulnerable service to only those remote hosts which have a known
need to use it. |
contains 10 rules |
XinetdgroupThe xinetd service acts as a dedicated listener for some
network services (mostly, obsolete ones) and can be used to provide access
controls and perform some logging. It has been largely obsoleted by other
features, and it is not installed by default. The older Inetd service
is not even available as part of Red Hat Enterprise Linux 6. |
contains 1 rule |
Uninstall xinetd PackageruleThe xinetd package can be uninstalled with the following command:
$ sudo yum erase xinetd
identifiers:
CCE-27005-8, DISA FSO RHEL-06-000204 references:
CM-7, 305, Test attestation on 20121026 by DS Remediation script:if rpm -qa | grep -q xinetd; then
yum -y remove xinetd
fi
|
TelnetgroupThe telnet protocol does not provide confidentiality or integrity
for information transmitted on the network. This includes authentication
information such as passwords. Organizations which use telnet should be
actively working to migrate to a more secure protocol. |
contains 2 rules |
Uninstall telnet-server PackageruleThe telnet-server package can be uninstalled with
the following command:
$ sudo yum erase telnet-server identifiers:
CCE-27073-6, DISA FSO RHEL-06-000206 references:
CM-7, 305, 381, Test attestation on 20121026 by DS Remediation script:if rpm -qa | grep -q telnet-server; then
yum -y remove telnet-server
fi
|
Remove telnet ClientsruleThe telnet client allows users to start connections to other
systems via the telnet protocol. identifiers:
CCE- |
Rlogin, Rsh, and RexecgroupThe Berkeley r-commands are legacy services which
allow cleartext remote access and have an insecure trust
model. |
contains 3 rules |
Uninstall rsh-server PackageruleThe rsh-server package can be uninstalled with
the following command:
$ sudo yum erase rsh-server
identifiers:
CCE-27062-9, DISA FSO RHEL-06-000213 references:
CM-7, 305, 381, Test attestation on 20121026 by DS Remediation script:yum -y erase rsh-server
|
Uninstal rsh PackageruleThe rsh package contains the client commands
for the rsh services identifiers:
CCE- references:
Test attestation on 20140530 by JL |
Remove Rsh Trust FilesruleThe files /etc/hosts.equiv and ~/.rhosts (in
each user's home directory) list remote hosts and users that are trusted by the
local system when using the rshd daemon.
To remove these files, run the following command to delete them from any
location:
$ sudo rm /etc/hosts.equiv
$ rm ~/.rhosts
identifiers:
CCE-27270-8, DISA FSO RHEL-06-000019 references:
CM-7, 1436, Test attestation on 20121026 by DS Remediation script:find -type f -name .rhosts -exec rm -f '{}' \;
rm /etc/hosts.equiv
|
NISgroupThe Network Information Service (NIS), also known as 'Yellow
Pages' (YP), and its successor NIS+ have been made obsolete by
Kerberos, LDAP, and other modern centralized authentication
services. NIS should not be used because it suffers from security
problems inherent in its design, such as inadequate protection of
important authentication information. |
contains 2 rules |
Uninstall ypserv PackageruleThe ypserv package can be uninstalled with
the following command:
$ sudo yum erase ypserv
identifiers:
CCE-27079-3, DISA FSO RHEL-06-000220 references:
CM-7, 305, 381, Test attestation on 20121026 by DS Remediation script:if rpm -qa | grep -q ypserv; then
yum -y remove ypserv
fi
|
Remove NIS ClientruleThe Network Information Service (NIS), formerly known as Yellow Pages,
is a client-server directory service protocol used to distribute system configuration
files. The NIS client (ypbind) was used to bind a machine to an NIS server
and receive the distributed configuration files. identifiers:
CCE- |
TFTP Servergroup
TFTP is a lightweight version of the FTP protocol which has
traditionally been used to configure networking equipment. However,
TFTP provides little security, and modern versions of networking
operating systems frequently support configuration via SSH or other
more secure protocols. A TFTP server should be run only if no more
secure method of supporting existing equipment can be
found. |
contains 2 rules |
Uninstall tftp-server Packagerule
The tftp-server package can be removed with the following command:
$ sudo yum erase tftp-server
identifiers:
CCE-26946-4, DISA FSO RHEL-06-000222 references:
CM-7, 305, Test attestation on 20121026 by DS |
Remove tftpruleTrivial File Transfer Protocol (TFTP) is a simple file transfer protocol,
typically used to automatically transfer configuration or boot files between machines.
TFTP does not support authentication and can be easily hacked. The package
tftp is a client program that allows for connections to a tftp server.
identifiers:
CCE- |
Base ServicesgroupThis section addresses the base services that are installed on a
Red Hat Enterprise Linux 6 default installation which are not covered in other
sections. Some of these services listen on the network and
should be treated with particular discretion. Other services are local
system utilities that may or may not be extraneous. In general, system services
should be disabled if not required. |
contains 1 rule |
Disable Red Hat Network Service (rhnsd)ruleThe Red Hat Network service automatically queries Red Hat Network
servers to determine whether there are any actions that should be executed,
such as package updates. This only occurs if the system was registered to an
RHN server or satellite and managed as such.
The rhnsd service can be disabled with the following command:
$ sudo chkconfig rhnsd off
identifiers:
CCE-26846-6, DISA FSO RHEL-06-000009 references:
CM-7, 382, Test attestation on 20121024 by DS Remediation script:#
# Disable rhnsd for all run levels
#
/sbin/chkconfig --level 0123456 rhnsd off
#
# Stop rhnsd if currently running
#
/sbin/service rhnsd stop
|
Cron and At DaemonsgroupThe cron and at services are used to allow commands to
be executed at a later time. The cron service is required by almost
all systems to perform necessary maintenance tasks, while at may or
may not be required on a given system. Both daemons should be
configured defensively. |
contains 2 rules |
Enable cron ServiceruleThe crond service is used to execute commands at
preconfigured times. It is required by almost all systems to perform necessary
maintenance tasks, such as notifying root of system activity.
The crond service can be enabled with the following command:
$ sudo chkconfig --level 2345 crond on
identifiers:
CCE-27070-2, DISA FSO RHEL-06-000224 references:
CM-7, Test attestation on 20121024 by DS Remediation script:#
# Enable crond for all run levels
#
/sbin/chkconfig --level 0123456 crond on
#
# Start crond if not currently running
#
/sbin/service crond start
|
Disable At Service (atd)ruleThe at and batch commands can be used to
schedule tasks that are meant to be executed only once. This allows delayed
execution in a manner similar to cron, except that it is not
recurring. The daemon atd keeps track of tasks scheduled via
at and batch, and executes them at the specified time.
The atd service can be disabled with the following command:
$ sudo chkconfig atd off
identifiers:
CCE-27249-2, DISA FSO RHEL-06-000262 references:
CM-7, 381 Remediation script:#
# Disable atd for all run levels
#
/sbin/chkconfig --level 0123456 atd off
#
# Stop atd if currently running
#
/sbin/service atd stop
|
SSH ServergroupThe SSH protocol is recommended for remote login and
remote file transfer. SSH provides confidentiality and integrity
for data exchanged between two systems, as well as server
authentication, through the use of public key cryptography. The
implementation included with the system is called OpenSSH, and more
detailed documentation is available from its website,
http://www.openssh.org. Its server program is called sshd and
provided by the RPM package openssh-server. |
contains 9 rules |
Configure OpenSSH Server if NecessarygroupIf the system needs to act as an SSH server, then
certain changes should be made to the OpenSSH daemon configuration
file /etc/ssh/sshd_config. The following recommendations can be
applied to this file. See the sshd_config(5) man page for more
detailed information. |
contains 9 rules |
Allow Only SSH Protocol 2ruleOnly SSH protocol version 2 connections should be
permitted. The default setting in
/etc/ssh/sshd_config is correct, and can be
verified by ensuring that the following
line appears:
Protocol 2
identifiers:
CCE-27072-8, DISA FSO RHEL-06-000227 references:
AC-3(10), IA-5(1)(c), 776, 774, 1436, Test attestation on 20121024 by DS Remediation script:grep -qi ^Protocol /etc/ssh/sshd_config && \
sed -i "s/Protocol.*/Protocol 2/gI" /etc/ssh/sshd_config
if ! [ $? -eq 0 ]; then
echo "Protocol 2" >> /etc/ssh/sshd_config
fi
|
Limit Users' SSH AccessruleBy default, the SSH configuration allows any user with an account
to access the system. In order to specify the users that are allowed to login
via SSH and deny all other users, add or correct the following line in the
/etc/ssh/sshd_config file:
DenyUsers USER1 USER2
Where USER1 and USER2 are valid user names.
identifiers:
CCE-27556-0 references:
AC-3, http://iase.disa.mil/stigs/cci/Pages/index.aspx |
Set SSH Idle Timeout IntervalruleSSH allows administrators to set an idle timeout
interval.
After this interval has passed, the idle user will be
automatically logged out.
To set an idle timeout interval, edit the following line in /etc/ssh/sshd_config as
follows:
ClientAliveInterval 300
The timeout interval is given in seconds. To have a timeout
of 15 minutes, set interval to 900.
If a shorter timeout has already been set for the login
shell, that value will preempt any SSH
setting made here. Keep in mind that some processes may stop SSH
from correctly detecting that the user is idle.
identifiers:
CCE-26919-1, DISA FSO RHEL-06-000230 references:
AC-2(5), SA-8, 879, 1133, Test attestation on 20121024 by DS Remediation script:sshd_idle_timeout_value="300"
grep -q ^ClientAliveInterval /etc/ssh/sshd_config && \
sed -i "s/ClientAliveInterval.*/ClientAliveInterval $sshd_idle_timeout_value/g" /etc/ssh/sshd_config
if ! [ $? -eq 0 ]; then
echo "ClientAliveInterval $sshd_idle_timeout_value" >> /etc/ssh/sshd_config
fi
|
Disable SSH Support for .rhosts FilesruleSSH can emulate the behavior of the obsolete rsh
command in allowing users to enable insecure access to their
accounts via .rhosts files.
To ensure this behavior is disabled, add or correct the
following line in /etc/ssh/sshd_config:
IgnoreRhosts yes
identifiers:
CCE-27124-7, DISA FSO RHEL-06-000234 references:
AC-3, 765, 766 Remediation script:grep -q ^IgnoreRhosts /etc/ssh/sshd_config && \
sed -i "s/IgnoreRhosts.*/IgnoreRhosts yes/g" /etc/ssh/sshd_config
if ! [ $? -eq 0 ]; then
echo "IgnoreRhosts yes" >> /etc/ssh/sshd_config
fi
|
Disable Host-Based AuthenticationruleSSH's cryptographic host-based authentication is
more secure than .rhosts authentication. However, it is
not recommended that hosts unilaterally trust one another, even
within an organization.
To disable host-based authentication, add or correct the
following line in /etc/ssh/sshd_config:
HostbasedAuthentication no
identifiers:
CCE-27091-8, DISA FSO RHEL-06-000236 references:
AC-3, 765, 766, Test attestation on 20121024 by DS Remediation script:grep -q ^HostbasedAuthentication /etc/ssh/sshd_config && \
sed -i "s/HostbasedAuthentication.*/HostbasedAuthentication no/g" /etc/ssh/sshd_config
if ! [ $? -eq 0 ]; then
echo "HostbasedAuthentication no" >> /etc/ssh/sshd_config
fi
|
Disable SSH Root LoginruleThe root user should never be allowed to login to a
system directly over a network.
To disable root login via SSH, add or correct the following line
in /etc/ssh/sshd_config:
PermitRootLogin no
identifiers:
CCE-27100-7, DISA FSO RHEL-06-000237 references:
AC-3, AC-6(2), IA-2(1), 770, Test attestation on 20121024 by DS Remediation script:
SSHD_CONFIG='/etc/ssh/sshd_config'
# Obtain line number of first uncommented case-insensitive occurrence of Match
# block directive (possibly prefixed with whitespace) present in $SSHD_CONFIG
FIRST_MATCH_BLOCK=$(sed -n '/^[[:space:]]*Match[^\n]*/I{=;q}' $SSHD_CONFIG)
# Obtain line number of first uncommented case-insensitive occurence of
# PermitRootLogin directive (possibly prefixed with whitespace) present in
# $SSHD_CONFIG
FIRST_PERMIT_ROOT_LOGIN=$(sed -n '/^[[:space:]]*PermitRootLogin[^\n]*/I{=;q}' $SSHD_CONFIG)
# Case: Match block directive not present in $SSHD_CONFIG
if [ -z "$FIRST_MATCH_BLOCK" ]
then
# Case: PermitRootLogin directive not present in $SSHD_CONFIG yet
if [ -z "$FIRST_PERMIT_ROOT_LOGIN" ]
then
# Append 'PermitRootLogin no' at the end of $SSHD_CONFIG
echo -e "\nPermitRootLogin no" >> $SSHD_CONFIG
# Case: PermitRootLogin directive present in $SSHD_CONFIG already
else
# Replace first uncommented case-insensitive occurrence
# of PermitRootLogin directive
sed -i "$FIRST_PERMIT_ROOT_LOGIN s/^[[:space:]]*PermitRootLogin.*$/PermitRootLogin no/I" $SSHD_CONFIG
fi
# Case: Match block directive present in $SSHD_CONFIG
else
# Case: PermitRootLogin directive not present in $SSHD_CONFIG yet
if [ -z "$FIRST_PERMIT_ROOT_LOGIN" ]
then
# Prepend 'PermitRootLogin no' before first uncommented
# case-insensitive occurrence of Match block directive
sed -i "$FIRST_MATCH_BLOCK s/^\([[:space:]]*Match[^\n]*\)/PermitRootLogin no\n\1/I" $SSHD_CONFIG
# Case: PermitRootLogin directive present in $SSHD_CONFIG and placed
# before first Match block directive
elif [ "$FIRST_PERMIT_ROOT_LOGIN" -lt "$FIRST_MATCH_BLOCK" ]
then
# Replace first uncommented case-insensitive occurrence
# of PermitRootLogin directive
sed -i "$FIRST_PERMIT_ROOT_LOGIN s/^[[:space:]]*PermitRootLogin.*$/PermitRootLogin no/I" $SSHD_CONFIG
# Case: PermitRootLogin directive present in $SSHD_CONFIG and placed
# after first Match block directive
else
# Prepend 'PermitRootLogin no' before first uncommented
# case-insensitive occurrence of Match block directive
sed -i "$FIRST_MATCH_BLOCK s/^\([[:space:]]*Match[^\n]*\)/PermitRootLogin no\n\1/I" $SSHD_CONFIG
fi
fi
|
Disable SSH Access via Empty PasswordsruleTo explicitly disallow remote login from accounts with
empty passwords, add or correct the following line in
/etc/ssh/sshd_config:
PermitEmptyPasswords no
Any accounts with empty passwords should be disabled immediately, and PAM configuration
should prevent users from being able to assign themselves empty passwords.
identifiers:
CCE-26887-0, DISA FSO RHEL-06-000239 references:
AC-3, 765, 766, Test attestation on 20121024 by DS Remediation script:grep -q ^PermitEmptyPasswords /etc/ssh/sshd_config && \
sed -i "s/PermitEmptyPasswords.*/PermitEmptyPasswords no/g" /etc/ssh/sshd_config
if ! [ $? -eq 0 ]; then
echo "PermitEmptyPasswords no" >> /etc/ssh/sshd_config
fi
|
Enable SSH Warning Bannerrule
To enable the warning banner and ensure it is consistent
across the system, add or correct the following line in /etc/ssh/sshd_config:
Banner /etc/issue
Another section contains information on how to create an
appropriate system-wide warning banner.
identifiers:
CCE-27112-2, DISA FSO RHEL-06-000240 references:
AC-8(a), 48, Test attestation on 20121024 by DS Remediation script:grep -q ^Banner /etc/ssh/sshd_config && \
sed -i "s/Banner.*/Banner \/etc\/issue/g" /etc/ssh/sshd_config
if ! [ $? -eq 0 ]; then
echo "Banner /etc/issue" >> /etc/ssh/sshd_config
fi
|
Use Only Approved CiphersruleLimit the ciphers to those algorithms which are FIPS-approved.
Counter (CTR) mode is also preferred over cipher-block chaining (CBC) mode.
The following line in /etc/ssh/sshd_config
demonstrates use of FIPS-approved ciphers:
Ciphers aes128-ctr,aes192-ctr,aes256-ctr,aes128-cbc,3des-cbc,aes192-cbc,aes256-cbc
The man page sshd_config(5) contains a list of supported ciphers.
identifiers:
CCE-26555-3, DISA FSO RHEL-06-000243 references:
AC-3, AC-17(2), SI-7, IA-5(1)(c), IA-7, 803, 1144, 1145, 1146, Test attestation on 20121024 by DS Remediation script:grep -q ^Ciphers /etc/ssh/sshd_config && \
sed -i "s/Ciphers.*/Ciphers aes128-ctr,aes192-ctr,aes256-ctr,aes128-cbc,3des-cbc,aes192-cbc,aes256-cbc/g" /etc/ssh/sshd_config
if ! [ $? -eq 0 ]; then
echo "Ciphers aes128-ctr,aes192-ctr,aes256-ctr,aes128-cbc,3des-cbc,aes192-cbc,aes256-cbc" >> /etc/ssh/sshd_config
fi
|
X Window SystemgroupThe X Window System implementation included with the
system is called X.org. |
contains 1 rule |
Disable X WindowsgroupUnless there is a mission-critical reason for the
system to run a graphical user interface, ensure X is not set to start
automatically at boot and remove the X Windows software packages.
There is usually no reason to run X Windows
on a dedicated server machine, as it increases the system's attack surface and consumes
system resources. Administrators of server systems should instead login via
SSH or on the text console. |
contains 1 rule |
Remove the X Windows Package GroupruleRemoving all packages which constitute the X Window System
ensures users or malicious software cannot start X.
To do so, run the following command:
$ sudo yum groupremove "X Window System"
identifiers:
CCE-27198-1, DISA FSO RHEL-06-000291 references:
366, Test attestation on 20121025 by DS |
Avahi ServergroupThe Avahi daemon implements the DNS Service Discovery
and Multicast DNS protocols, which provide service and host
discovery on a network. It allows a system to automatically
identify resources on the network, such as printers or web servers.
This capability is also known as mDNSresponder and is a major part
of Zeroconf networking. |
contains 1 rule |
Disable Avahi Server if PossiblegroupBecause the Avahi daemon service keeps an open network
port, it is subject to network attacks.
Disabling it can reduce the system's vulnerability to such attacks.
|
contains 1 rule |
Disable Avahi Server Softwarerule
The avahi-daemon service can be disabled with the following command:
$ sudo chkconfig avahi-daemon off
identifiers:
CCE-27087-6, DISA FSO RHEL-06-000246 references:
CM-7, 366 |
Print SupportgroupThe Common Unix Printing System (CUPS) service provides both local
and network printing support. A system running the CUPS service can accept
print jobs from other systems, process them, and send them to the appropriate
printer. It also provides an interface for remote administration through a web
browser. The CUPS service is installed and activated by default. The project
homepage and more detailed documentation are available at http://www.cups.org.
|
contains 1 rule |
Disable the CUPS Servicerule
The cups service can be disabled with the following command:
$ sudo chkconfig cups off
identifiers:
CCE-26899-5 references:
CM-7 Remediation script:#
# Disable cups for all run levels
#
/sbin/chkconfig --level 0123456 cups off
#
# Stop cups if currently running
#
/sbin/service cups stop
|
DHCPgroupThe Dynamic Host Configuration Protocol (DHCP) allows
systems to request and obtain an IP address and other configuration
parameters from a server.
This guide recommends configuring networking on clients by manually editing
the appropriate files under /etc/sysconfig. Use of DHCP can make client
systems vulnerable to compromise by rogue DHCP servers, and should be avoided
unless necessary. If using DHCP is necessary, however, there are best practices
that should be followed to minimize security risk.
|
contains 1 rule |
Disable DHCP Servergroup
The DHCP server dhcpd is not installed or activated by
default. If the software was installed and activated, but the
system does not need to act as a DHCP server, it should be disabled
and removed.
|
contains 1 rule |
Uninstall DHCP Server PackageruleIf the system does not need to act as a DHCP server,
the dhcp package can be uninstalled.
The dhcp package can be removed with the following command:
$ sudo yum erase dhcp
identifiers:
CCE-27120-5 references:
CM-7, 366, Test attestation on 20121024 by DS |
Network Time ProtocolgroupThe Network Time Protocol is used to manage the system
clock over a network. Computer clocks are not very accurate, so
time will drift unpredictably on unmanaged systems. Central time
protocols can be used both to ensure that time is consistent among
a network of machines, and that their time is consistent with the
outside world.
If every system on a network reliably reports the same time, then it is much
easier to correlate log messages in case of an attack. In addition, a number of
cryptographic protocols (such as Kerberos) use timestamps to prevent certain
types of attacks. If your network does not have synchronized time, these
protocols may be unreliable or even unusable.
Depending on the specifics of the network, global time accuracy may be just as
important as local synchronization, or not very important at all. If your
network is connected to the Internet, using a
public timeserver (or one provided by your enterprise) provides globally
accurate timestamps which may be essential in investigating or responding to
an attack which originated outside of your network.
A typical network setup involves a small number of internal systems operating as NTP
servers, and the remainder obtaining time information from those
internal servers.
More information on how to configure the NTP server software,
including configuration of cryptographic authentication for
time data, is available at http://www.ntp.org.
|
contains 3 rules |
Enable the NTP Daemonrule
The ntpd service can be enabled with the following command:
$ sudo chkconfig --level 2345 ntpd on
identifiers:
CCE-27093-4, DISA FSO RHEL-06-000247 references:
AU-8(1), 160, Test attestation on 20121024 by DS Remediation script:#
# Enable ntpd for all run levels
#
/sbin/chkconfig --level 0123456 ntpd on
#
# Start ntpd if not currently running
#
/sbin/service ntpd start
|
Specify a Remote NTP ServerruleTo specify a remote NTP server for time synchronization, edit
the file /etc/ntp.conf. Add or correct the following lines,
substituting the IP or hostname of a remote NTP server for ntpserver:
server ntpserver
This instructs the NTP software to contact that remote server to obtain time
data.
identifiers:
CCE-27098-3, DISA FSO RHEL-06-000248 references:
AU-8(1), 160, Test attestation on 20121024 by DS |
Specify Additional Remote NTP ServersruleAdditional NTP servers can be specified for time synchronization
in the file /etc/ntp.conf. To do so, add additional lines of the
following form, substituting the IP address or hostname of a remote NTP server for
ntpserver:
server ntpserver
identifiers:
CCE-26958-9 references:
AU-8(1) |
Mail Server Softwaregroup
Mail servers are used to send and receive email over the network.
Mail is a very common service, and Mail Transfer Agents (MTAs) are obvious
targets of network attack.
Ensure that machines are not running MTAs unnecessarily,
and configure needed MTAs as defensively as possible.
Very few systems at any site should be configured to directly receive email over the
network. Users should instead use mail client programs to retrieve email
from a central server that supports protocols such as IMAP or POP3.
However, it is normal for most systems to be independently capable of sending email,
for instance so that cron jobs can report output to an administrator.
Most MTAs, including Postfix, support a submission-only mode in which mail can be sent from
the local system to a central site MTA (or directly delivered to a local account),
but the system still cannot receive mail directly over a network.
The alternatives program in Red Hat Enterprise Linux permits selection of other mail server software
(such as Sendmail), but Postfix is the default and is preferred.
Postfix was coded with security in mind and can also be more effectively contained by
SELinux as its modular design has resulted in separate processes performing specific actions.
More information is available on its website, http://www.postfix.org.
|
contains 1 rule |
Configure SMTP For Mail ClientsgroupThis section discusses settings for Postfix in a submission-only
e-mail configuration. |
contains 1 rule |
Disable Postfix Network Listeningrule
Edit the file /etc/postfix/main.cf to ensure that only the following
inet_interfaces line appears:
inet_interfaces = localhost
identifiers:
CCE-26780-7, DISA FSO RHEL-06-000249 references:
CM-7, 382, Test attestation on 20121024 by DS |
LDAPgroupLDAP is a popular directory service, that is, a
standardized way of looking up information from a central database.
Red Hat Enterprise Linux 6 includes software that enables a system to act as both
an LDAP client and server.
|
contains 1 rule |
Configure OpenLDAP ServergroupThis section details some security-relevant settings
for an OpenLDAP server. Installation and configuration of OpenLDAP on Red Hat Enterprise Linux 6 is available at:
https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Deployment_Guide/ch-Directory_Servers.html.
|
contains 1 rule |
Uninstall openldap-servers PackageruleThe openldap-servers package should be removed if not in use.
Is this machine the OpenLDAP server? If not, remove the package.
$ sudo yum erase openldap-servers
The openldap-servers RPM is not installed by default on Red Hat Enterprise Linux 6
machines. It is needed only by the OpenLDAP server, not by the
clients which use LDAP for authentication. If the system is not
intended for use as an LDAP Server it should be removed.
identifiers:
CCE-26858-1, DISA FSO RHEL-06-000256 references:
CM-7, 366, Test attestation on 20121024 by DS |
FTP ServergroupFTP is a common method for allowing remote access to
files. Like telnet, the FTP protocol is unencrypted, which means
that passwords and other data transmitted during the session can be
captured and that the session is vulnerable to hijacking.
Therefore, running the FTP server software is not recommended.
However, there are some FTP server configurations which may
be appropriate for some environments, particularly those which
allow only read-only anonymous access as a means of downloading
data available to the public. |
contains 1 rule |
Disable vsftpd if Possiblegroup |
contains 1 rule |
Uninstall vsftpd Packagerule
The vsftpd package can be removed with the following command:
$ sudo yum erase vsftpd
identifiers:
CCE-26687-4 references:
CM-7, 1436 |
Web ServergroupThe web server is responsible for providing access to
content via the HTTP protocol. Web servers represent a significant
security risk because:
The HTTP port is commonly probed by malicious sourcesWeb server software is very complex, and includes a long
history of vulnerabilitiesThe HTTP protocol is unencrypted and vulnerable to passive
monitoring
The system's default web server software is Apache 2 and is
provided in the RPM package httpd. |
contains 1 rule |
Disable Apache if PossiblegroupIf Apache was installed and activated, but the system
does not need to act as a web server, then it should be disabled
and removed from the system.
|
contains 1 rule |
Uninstall httpd Packagerule
The httpd package can be removed with the following command:
$ sudo yum erase httpd
identifiers:
CCE-27133-8 references:
CM-7 Remediation script:if rpm -qa | grep -q httpd; then
yum -y remove httpd
fi
|
SNMP ServergroupThe Simple Network Management Protocol allows
administrators to monitor the state of network devices, including
computers. Older versions of SNMP were well-known for weak
security, such as plaintext transmission of the community string
(used for authentication) and usage of easily-guessable
choices for the community string. |
contains 1 rule |
Disable SNMP Server if PossiblegroupThe system includes an SNMP daemon that allows for its remote
monitoring, though it not installed by default. If it was installed and
activated but is not needed, the software should be disabled and removed.
|
contains 1 rule |
Uninstall net-snmp PackageruleThe net-snmp package provides the snmpd service.
The net-snmp package can be removed with the following command:
$ sudo yum erase net-snmp
identifiers:
CCE-26332-7 Remediation script:if rpm -qa | grep -q net-snmp; then
yum -y remove net-snmp
fi
|