1.1.4 Ensure nosuid option set on /tmp partition

Information

The nosuidmount option specifies that the filesystem cannot contain setuid files.
Rationale:
Since the /tmpfilesystem 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 nosuidto 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

Notes:

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

See Also

https://workbench.cisecurity.org/files/2429

Item Details

Category: ACCESS CONTROL

References: 800-53|AC-6(1), CSCv6|13, CSCv7|5.1

Plugin: Unix

Control ID: 7783c939dbae0ee98828d4c16c993b1d78b31b7951395016c658919d843501fa