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CIS Ubuntu 14.04 LTS - 1.1.21 Disable Automounting

DevOps & Security
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Disable autofs to prevent automatic mounting of removable media devices

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Source SKILL.md: https://github.com/CyberStrikeus/CyberStrike/blob/HEAD/.cyberstrike/skill/CIS_benchmarks/Operating_Systems/Ubuntu/CIS_Ubuntu_Linux_14.04_LTS_Benchmark_v2.1.0/cis-ubuntu1404-v210-1-1-21/SKILL.md

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1.1.21 Disable Automounting (Scored)

Profile Applicability

  • Level 1 - Server
  • Level 2 - Workstation

Description

autofs allows automatic mounting of devices, typically including CD/DVDs and USB drives.

Rationale

With automounting enabled anyone with physical access could attach a USB drive or disc and have its contents available in system even if they lacked permissions to mount it themselves.

Audit Procedure

# Run the following commands to verify no start conditions listed for autofs:
initctl show-config autofs
# Expected output: autofs

Expected Result

The output should show autofs with no start conditions listed (no start on directives).

Remediation

# Remove or comment out start lines in /etc/init/autofs.conf:
#start on runlevel [2345]

Default Value

By default, autofs may be enabled.

Impact

The use of portable hard drives is very common for workstation users. If your organization allows the use of portable storage or media on workstations and physical access controls to workstations is considered adequate there is little value add in turning off automounting.

Notes

This control should align with the tolerance of the use of portable drives and optical media in the organization. On a server requiring an admin to manually mount media can be part of defense-in-depth to reduce the risk of unapproved software or information being introduced or proprietary software or information being exfiltrated.

References

  • CIS Ubuntu Linux 14.04 LTS Benchmark v2.1.0

Profile

  • Level 1