Ubuntu 22.04

Ubuntu 22.04 LTS must restrict access to the kernel message buffer

STIG ID: UBTU-22-213010 | SRG: SRG-OS-000138-GPOS-00069 | Severity: Low | CCI: CCI-001090 | Vulnerability ID: V-260472

Description

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

C-64201r953227_chk

Verify Ubuntu 22.04 LTS is configured to restrict access to the kernel message buffer by using the following command: $ sysctl kernel.dmesg_restrict kernel.dmesg_restrict = 1 If "kernel.dmesg_restrict" is not set to "1" or is missing, this is a finding. Verify that there are no configurations that enable the kernel dmesg function: $ sudo grep -ir 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.d/10-kernel-hardening.conf:kernel.dmesg_restrict = 1 If "kernel.dmesg_restrict" is not set to "1", is commented out, is missing, or conflicting results are returned, this is a finding.

Fix

F-64109r953228_fix

Configure Ubuntu 22.04 LTS to restrict access to the kernel message buffer. Add or modify the following line in the "/etc/sysctl.conf" file: 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 by using the following command: $ sudo sysctl --system