RHEL 9 must restrict exposed kernel pointer addresses access.

Severity
Group ID
Group Title
Version
Rule ID
Date
STIG Version
mediumV-257800SRG-OS-000132-GPOS-00067RHEL-09-213025SV-257800r1155700_rule2025-11-242
Description
It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. The sysctl --system command will load settings from all system configuration files. All configuration files are sorted by their filename in lexicographical order, regardless of the directories in which they reside. If multiple files specify the same option, the entry in the file with the lexicographically latest name will take precedence. Files are read from directories in the following list from top to bottom. Once a file of a given filename is loaded, any file of the same name in subsequent directories is ignored. /etc/sysctl.d/*.conf /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf /lib/sysctl.d/*.conf /etc/sysctl.conf Satisfies: SRG-OS-000132-GPOS-00067, SRG-OS-000433-GPOS-00192, SRG-OS-000480-GPOS-00227
ℹ️ Check
Verify RHEL 9 is configured to restrict exposed kernel pointer address access. Verify the runtime status of the "kernel.kptr_restrict" kernel parameter with the following command: $ sudo sysctl kernel.kptr_restrict kernel.kptr_restrict = 1 If "kernel.kptr_restrict" is not set to "1" or is missing, this is a finding.
✔️ Fix
Configure RHEL 9 to restrict exposed kernel pointer addresses access. Create a drop-in if it does not already exist: $ sudo vi /etc/sysctl.d/99-kernel_kptr_restrict.conf Add the following to the file: kernel.kptr_restrict = 1 Reload settings from all system configuration files with the following command: $ sudo sysctl --system