RHEL 9 must prevent files with the setuid and setgid bit set from being executed on the /boot/efi directory.

STIG ID: RHEL-09-231105  |  SRG: SRG-OS-000368-GPOS-00154 | Severity: medium |  CCI: CCI-000366,CCI-001764

Vulnerability Discussion

The "nosuid" mount option causes the system not to 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.

Satisfies: SRG-OS-000368-GPOS-00154, SRG-OS-000480-GPOS-00227

Check

Note: For systems that use BIOS, this requirement is Not Applicable.

Verify the /boot/efi directory is mounted with the "nosuid" option with the following command:

$ mount | grep '\s/boot/efi\s'

/dev/sda1 on /boot/efi type vfat (rw,nosuid,relatime,fmask=0077,dmask=0077,codepage=437,iocharset=ascii,shortname=winnt,errors=remount-ro)

If the /boot/efi file system does not have the "nosuid" option set, this is a finding.

Fix

Modify "/etc/fstab" to use the "nosuid" option on the "/boot/efi" directory.
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