cyberstrikeus Ensure nosuid option set on /var/tmp partition
Profile
Level 1 - Server / Level 1 - Workstation, Assessment: Automated
Description
The nosuid mount option specifies that the filesystem cannot contain setuid files.
Rationale
Since the /var/tmp filesystem is only intended for temporary file storage, set this option to ensure that users cannot create setuid files in /var/tmp.
Impact
None noted.
Audit Procedure
Command Line
Verify that the nosuid option is set for the /var/tmp mount.
# findmnt -kn /var/tmp | grep nosuid
Expected Result
/var/tmp /dev/sda3 ext4 rw,nosuid,nodev,noexec,relatime,seclabel
Remediation
Command Line
Edit the /etc/fstab file and add nosuid to the fourth field (mounting options) for the /var/tmp partition.
# Example:
# <device> /var/tmp <fstype> defaults,rw,nosuid,nodev,noexec,relatime 0 0
# Run the following command to remount /var/tmp with the configured options:
mount -o remount /var/tmp
Default Value
Not set by default.
References
- See the fstab(5) manual page for more information.
- NIST SP 800-53 Rev. 5: AC-3, MP-2
CIS Controls
v8 - 3.3 Configure Data Access Control Lists (IG 1, IG 2, IG 3) v7 - 14.6 Protect Information through Access Control Lists (IG 1, IG 2, IG 3)
MITRE ATT&CK Mappings: T1548, T1548.001 (TA0005) - M1022, M1038