RHEL 9 must prevent files with the setuid and setgid bit set from being executed on file systems that are imported via Network File System (NFS).

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-257856	RHEL-09-231075	SV-257856r1044938_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.

STIG	Date
Red Hat Enterprise Linux 9 Security Technical Implementation Guide	2024-12-04

Details

Check Text (C-61597r1044937_chk)

Note: If no NFS mounts are configured, this requirement is Not Applicable.

Verify RHEL 9 has the "nosuid" option configured for all NFS mounts with the following command:

$ grep nfs /etc/fstab

192.168.22.2:/mnt/export /data nfs4 rw,nosuid,nodev,noexec,sync,soft,sec=krb5:krb5i:krb5p

If the system is mounting file systems via NFS and the "nosuid" option is missing, this is a finding.

Fix Text (F-61521r925554_fix)

Update each NFS mounted file system to use the "nosuid" option on file systems that are being imported via NFS.