1.1.4 Ensure nosuid option set on /tmp partition

Information

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.

Solution

If using the /etc/fstab for configuring /tmp do the following:
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

If using systemd tmp.mount for configuring /tmp do the following:
Edit /etc/systemd/system/local-fs.target.wants/tmp.mount and add the nosuid option to the Options line
Example:

[Mount]
What=tmpfs
Where=/tmp
Type=tmpfs
Options=mode=1777,strictatime,noexec,nodev,nosuid

Run the following command to remount /tmp:

# mount -o remount,nosuid /tmp

Additional Information:

If the /etc/fstab includes /tmp it will take precedence over the tmp.mount file

See Also

https://workbench.cisecurity.org/files/3399

Item Details

Category: CONFIGURATION MANAGEMENT, SYSTEM AND SERVICES ACQUISITION

References: 800-53|CM-1, 800-53|CM-2, 800-53|CM-6, 800-53|CM-7, 800-53|CM-7(1), 800-53|CM-9, 800-53|SA-3, 800-53|SA-8, 800-53|SA-10, CSCv6|13, CSCv7|5.1

Plugin: Unix

Control ID: ebcdacb94ed4a15eb48ac8ca5fcb020e59371aaa0fb9084e143571a4b814692e