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

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-257862	RHEL-09-231105	SV-257862r958804_rule		Medium

Description
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

Description

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

STIG	Date
Red Hat Enterprise Linux 9 Security Technical Implementation Guide	2024-06-04

Details

Check Text ( C-61603r925571_chk )
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.

Check Text ( C-61603r925571_chk )

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 Text (F-61527r925572_fix)
Modify "/etc/fstab" to use the "nosuid" option on the "/boot/efi" directory.