RHEL 9 must mount /dev/shm with the nosuid option.

STIG ID: RHEL-09-231120  |  SRG: SRG-OS-000368-GPOS-00154 |  Severity: medium |  CCI: CCI-001764 |  Vulnerability Id: V-257865

Vulnerability Discussion

The "nosuid" mount option causes the system to not execute "setuid" and "setgid" files with owner privileges. This option must be used for mounting any file system not containing approved "setuid" and "setguid" files. Executing files from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.

Check

Verify "/dev/shm" is mounted with the "nosuid" option with the following command:

$ mount | grep /dev/shm

tmpfs on /dev/shm type tmpfs (rw,nodev,nosuid,noexec,seclabel)

If the /dev/shm file system is mounted without the "noexec" option, this is a finding.

Fix

Modify "/etc/fstab" to use the "nosuid" option on the "/dev/shm" file system.