Finding ID | Version | Rule ID | IA Controls | Severity |
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V-255907 | UBTU-18-010510 | SV-255907r880894_rule | Low |
Description |
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Restricting access to the kernel message buffer limits access only to root. This prevents attackers from gaining additional system information as a nonprivileged user. |
STIG | Date |
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Canonical Ubuntu 18.04 LTS Security Technical Implementation Guide | 2023-09-08 |
Check Text ( C-59584r880892_chk ) |
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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 (F-59527r880893_fix) |
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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 |