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V-261269

CAT II (Medium)

SLEM 5 must restrict access to the kernel message buffer.

Rule ID

SV-261269r1137695_rule

STIG

SUSE Linux Enterprise Micro (SLEM) 5 Security Technical Implementation Guide

Version

V1R4

CCIs

CCI-001090

Discussion

Restricting access to the kernel message buffer limits access only to root. This prevents attackers from gaining additional system information as a nonprivileged user.

Check Content

Verify SLEM 5 is configured to restrict access to the kernel message buffer with the following commands:

     > sudo sysctl kernel.dmesg_restrict
     kernel.dmesg_restrict = 1

If "kernel.dmesg_restrict" is not set to "1" or is missing, this is a finding.

Check that the configuration files are present to enable this kernel parameter:

     > sudo grep -r kernel.dmesg_restrict /run/sysctl.d/* /etc/sysctl.d/* /usr/local/lib/sysctl.d/* /usr/lib/sysctl.d/* /lib/sysctl.d/* /etc/sysctl.conf 2> /dev/null

     /etc/sysctl.conf:kernel.dmesg_restrict = 1
     /etc/sysctl.d/99-sysctl.conf:kernel.dmesg_restrict = 1

If "kernel.dmesg_restrict" is not set to "1", is missing or commented out, this is a finding.

If conflicting results are returned, this is a finding.

Fix Text

Configure SLEM 5 to restrict access to the kernel message buffer.

Set the system to the required kernel parameter by adding or modifying the following line in /etc/sysctl.conf or a config file in the /etc/sysctl.d/ directory:

kernel.dmesg_restrict = 1

Remove any configurations that conflict with the above from the following locations: 

/run/sysctl.d/
/etc/sysctl.d/
/usr/local/lib/sysctl.d/
/usr/lib/sysctl.d/
/lib/sysctl.d/
/etc/sysctl.conf

Reload settings from all system configuration files with the following command:

     $ sudo sysctl --system