cyberstrikeus Ensure nosuid option set on /tmp partition
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.
Impact
None noted.
Audit Procedure
Command Line
# If a /tmp partition exists, verify that the nosuid option is set
# Run the following command and verify that nothing is returned:
findmnt -n /tmp | grep -v nosuid
Expected Result
No output should be returned.
Remediation
Command Line
# 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
# OR Edit /etc/systemd/system/local-fs.target.wants/tmp.mount to add nosuid to the /tmp mount options:
# [Mount]
# Options=mode=1777,strictatime,noexec,nodev,nosuid
# Run the following command to remount /tmp:
mount -o remount,nosuid /tmp
Default Value
Not set by default.
References
- CIS Controls Version 7 - 5.1 Establish Secure Configurations: Maintain documented, standard security configuration standards for all authorized operating systems and software.
Profile
Level 1 - Server / Level 1 - Workstation, Assessment: Automated