STIG ID: UBTU-18-010510 | SRG: SRG-OS-000138-GPOS-00069 | Severity: low | CCI: | Vulnerability Id: V-255907
Restricting access to the kernel message buffer limits access only to root. This prevents attackers from gaining additional system information as a nonprivileged user.
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
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.