cyberstrikeus 1.1.4 Ensure nosuid option set on /tmp partition (Scored)
Profile Applicability
- Level 1 - Server
- Level 1 - Workstation
Description
The nosuid mount option specifies that the filesystem cannot contain setuid files.
Rationale
Since the /tmp filesystem is only intended for temporary file storage, set this option to ensure that users cannot create setuid files in /tmp.
Audit Procedure
mount | grep /tmp
# Verify that the nosuid option is set on /tmp
# Expected output: tmpfs on /tmp type tmpfs (rw,nosuid,nodev,noexec,relatime)
Expected Result
The output should show the nosuid option is set for the /tmp partition.
Remediation
# Edit the /etc/fstab file and add nosuid to the fourth field (mounting options)
# for the /tmp partition. See the fstab(5) manual page for more information.
# Run the following command to remount /tmp:
mount -o remount,nosuid /tmp
Default Value
By default, the nosuid option is not set on /tmp.
References
- CIS Ubuntu Linux 14.04 LTS Benchmark v2.1.0
Notes
systemd includes the tmp.mount service which should be used instead of configuring /etc/fstab. Mounting options are configured in the Options setting in /etc/systemd/system/tmp.mount.
Profile
- Level 1