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cis-ubuntu1604-v200-1-1-3

DevOps & Security
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Ensure nodev option set on /tmp 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_16.04_LTS_Benchmark_v2.0.0/cis-ubuntu1604-v200-1-1-3/SKILL.md

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Ensure nodev option set on /tmp partition

Description

The nodev mount option specifies that the filesystem cannot contain special devices.

Rationale

Since the /tmp filesystem is not intended to support devices, set this option to ensure that users cannot attempt to create block or character special devices in /tmp.

Impact

None noted.

Audit Procedure

Command Line

# Verify that the nodev option is set if a /tmp partition exists
# Run the following command and verify that nothing is returned:
findmnt -n /tmp | grep -v nodev

Expected Result

No output should be returned.

Remediation

Command Line

# Edit the /etc/fstab file OR the /etc/systemd/system/local-fs.target.wants/tmp.mount file:

# If /etc/fstab is used to mount /tmp:
# Edit the /etc/fstab file and add nodev 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,nodev /tmp

# OR If systemd is used to mount /tmp:
# Edit /etc/systemd/system/local-fs.target.wants/tmp.mount to add nodev to the /tmp mount options:
# [Mount]
# Options=mode=1777,strictatime,noexec,nodev,nosuid

# Run the following command to restart the systemd daemon:
systemctl daemon-reload

# Run the following command to restart tmp.mount
systemctl restart tmp.mount

Default Value

Not set by default.

References

  • CIS Controls Version 7 - 5.1 Establish Secure Configurations: Maintain documented, standard security configuration standards for all authorized operating systems and software.

Profile

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