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V-255921

CAT III (Low)

The SUSE operating system must restrict access to the kernel message buffer.

Rule ID

SV-255921r1137695_rule

STIG

SUSE Linux Enterprise Server 15 Security Technical Implementation Guide

Version

V2R7

CCIs

None

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 the operating system 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 the operating system 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