# Cis Ubuntu2004 V300 1 1 2 5 3

> Ensure nosuid option set on /var/tmp partition

- Skill: `cyberstrikeus/cis-ubuntu2004-v300-1-1-2-5-3` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/cis-ubuntu2004-v300-1-1-2-5-3`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/cis-ubuntu2004-v300-1-1-2-5-3/raw
- Safety review: PASS (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: cyberstrikeus (https://skillmd.com/u/cyberstrikeus)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/cyberstrikeus/cis-ubuntu2004-v300-1-1-2-5-3

---


# 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`.

## Audit Procedure

### Command Line

- IF - a separate partition exists for `/var/tmp`, verify that the `nosuid` option is set.
  Run the following command to verify that the `nosuid` mount option is set.
  Example:

```bash
# findmnt -kn /var/tmp | grep -v nosuid
```

Nothing should be returned

## Expected Result

Nothing should be returned

## Remediation

### Command Line

- IF - a separate partition exists for `/var/tmp`.
  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:

```bash
# mount -o remount /var/tmp
```

## 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-230521
5. RHEL 8 STIG STIG ID: RHEL-08-040133

## 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