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

Documentable No

Rule ID SV-257862r1155661_rule

CCI References

CCI-001764

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 Procedure

Note: For systems that use vfat file systems and 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.

Note: This control is not applicable to vfat file systems.

Fix Action

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