RHEL 9 must prevent files with the setuid and setgid bit set from being executed on file systems that contain user home directories.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-257851	RHEL-09-231050	SV-257851r958804_rule		Medium

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

Description

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. 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-61592r925538_chk )
Verify "/home" is mounted with the "nosuid" option with the following command: Note: If a separate file system has not been created for the user home directories (user home directories are mounted under "/"), this is automatically a finding, as the "nosuid" option cannot be used on the "/" system. $ mount \| grep /home tmpfs on /home type tmpfs (rw,nodev,nosuid,noexec,seclabel) If the "/home" file system is mounted without the "nosuid" option, this is a finding.

Check Text ( C-61592r925538_chk )

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

Note: If a separate file system has not been created for the user home directories (user home directories are mounted under "/"), this is automatically a finding, as the "nosuid" option cannot be used on the "/" system.

$ mount | grep /home

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

If the "/home" file system is mounted without the "nosuid" option, this is a finding.

Fix Text (F-61516r925539_fix)
Modify "/etc/fstab" to use the "nosuid" option on the "/home" directory.