Cis Ubuntu2004 V300 1 1 2 2 3

Ensure nosuid option set on /dev/shm partition

Profile

Level 1 - Server, Level 1 - Workstation, Assessment: Automated

Description

The nosuid mount option specifies that the filesystem cannot contain setuid files.

Rationale

Setting this option on a file system prevents users from introducing privileged programs onto the system and allowing non-root users to execute them.

Audit Procedure

Command Line

• IF - a separate partition exists for /dev/shm, verify that the nosuid option is set.

# findmnt -kn /dev/shm | grep -v 'nosuid'

Nothing should be returned

Expected Result

Nothing should be returned

Remediation

Command Line

• IF - a separate partition exists for /dev/shm. Edit the /etc/fstab file and add nosuid to the fourth field (mounting options) for the /dev/shm partition. See the fstab(5) manual page for more information. Example:

tmpfs /dev/shm   tmpfs   defaults,rw,nosuid,nodev,noexec,relatime   0 0

Run the following command to remount /dev/shm with the configured options:

# mount -o remount /dev/shm

Note: It is recommended to use tmpfs as the device/filesystem type as /dev/shm is used as shared memory space by applications.

Default Value

Not configured by default.

References

1. NIST SP 800-53 Rev. 5: AC-3, MP-2
2. NIST SP 800-53 Revision 5 :: CM-7 (2)
3. RHEL 8 STIG Vul ID: V-230509
4. RHEL 8 STIG Rule ID: SV-230509r854050

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 | M1038