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cis-ubuntu2004-v300-1-1-2-2-4

DevOps & Security
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Ensure noexec option set on /dev/shm partition

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Source SKILL.md: https://github.com/CyberStrikeus/CyberStrike/blob/HEAD/.cyberstrike/skill/CIS_benchmarks/Operating_Systems/Ubuntu/CIS_Ubuntu_Linux_20.04_LTS_Benchmark_v3.0.0/cis-ubuntu2004-v300-1-1-2-2-4/SKILL.md

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Ensure noexec option set on /dev/shm partition

Profile

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

Description

The noexec mount option specifies that the filesystem cannot contain executable binaries.

Rationale

Setting this option on a file system prevents users from executing programs from shared memory. This deters users from introducing potentially malicious software on the system.

Audit Procedure

Command Line

  • IF - a separate partition exists for /dev/shm, verify that the noexec option is set.
# findmnt -kn /dev/shm | grep -v 'noexec'

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 noexec 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. See the fstab(5) manual page for more information.
  2. NIST SP 800-53 Rev. 5: AC-3, MP-2
  3. NIST SP 800-53 Revision 5 :: CM-7 (2)
  4. RHEL 8 STIG Vul ID: V-230510
  5. RHEL 8 STIG Rule ID: SV-230510r854051

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: T1204, T1204.002 | TA0005 | M1022