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).

STIG ID: RHEL-09-231075  |  SRG: SRG-OS-000480-GPOS-00227 | Severity: medium |  CCI: CCI-000366

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.

Check

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

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

$ cat /etc/fstab | grep nfs

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

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