Profile Applicability:
 • Level 1

Description:
 The nosuid mount option prevents the operation of set-user-identifier (setuid) and set-group-identifier (setgid) bits on executable files in the mounted filesystem. Applying this option to /home helps prevent privilege escalation by disallowing setuid and setgid programs from running in user directories.

Rationale:
 Setting the nosuid option on /home reduces the risk that users or attackers could exploit setuid/setgid binaries within their home directories to gain elevated privileges.

Impact:
 Pros:

  • Mitigates privilege escalation attacks via setuid/setgid binaries in /home.

  • Improves overall system security posture.

Cons:

  • May affect applications that require setuid/setgid binaries in /home (rare).

Default Value:
 The nosuid option is typically not set on /home unless explicitly configured.

Pre-requisites:

  • Root or sudo privileges to modify /etc/fstab and remount filesystems.

  • /home must be mounted as a separate partition.

Remediation:

Test Plan:

Using Linux command line:

  1. Check current mount options for /home:

     mount | grep /home

  2. Verify if nosuid is present in /etc/fstab for /home:

     grep /home /etc/fstab
    Expected output: Mount options for /home include nosuid.


Implementation Plan:

Using Linux command line:

  1. Edit /etc/fstab to add nosuid to the /home mount options. Example:
    /dev/<partition>  /home  ext4  defaults,nodev,nosuid,noexec  0  0


  2. Remount /home with new options:

     mount -o remount,nosuid /home

  3. Verify mount options:

     mount | grep /home

Backout Plan:

Using Linux command line:

  1. Remove nosuid from /home mount options in /etc/fstab.

  2. Remount /home without nosuid:

     mount -o remount /home

  3. Verify mount options:

     mount | grep /home

References: