cis-gcp-cos-1-1-1-1

name	cis-gcp-cos-1.1.1.1
description	Ensure mounting of udf filesystems is disabled
category	cis-gcp-cos
version	1.2.0
author	cyberstrike-official
tags	["cis","gcp","container-optimized-os","filesystem","partitions","mount-options"]
cis_id	1.1.1.1
cis_benchmark	CIS Google Container-Optimized OS Benchmark v1.2.0
tech_stack	["gcp","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

1.1.1.1 Ensure mounting of udf filesystems is disabled (Automated)

Description

The udf filesystem type is the universal disk format used to implement ISO/IEC 13346 and ECMA-167 specifications. This is an open vendor filesystem type for data storage on a broad range of media. This filesystem type is necessary to support writing DVDs and newer optical disc formats.

Rationale

Removing support for unneeded filesystem types reduces the local attack surface of the system. If this filesystem type is not needed, disable it.

Audit Procedure

Run the following commands and verify the output is as indicated:

# modprobe -n -v udf
install /bin/true
# lsmod | grep udf
<No output>

Expected Result

• modprobe -n -v udf should return install /bin/true
• lsmod | grep udf should return no output

Remediation

Edit or create a file in the /etc/modprobe.d/ directory ending in .conf. Example: vim /etc/modprobe.d/udf.conf and add the following line:

install udf /bin/true

Run the following command to unload the udf module:

# rmmod udf

CIS Controls

Controls Version	Control	IG 1	IG 2	IG 3
v8	4.8 Uninstall or Disable Unnecessary Services on Enterprise Assets and Software - Uninstall or disable unnecessary services on enterprise assets and software, such as an unused file sharing service, web application module, or service function.		x	x
v8	5.5 Establish and Maintain an Inventory of Service Accounts - Establish and maintain an inventory of service accounts. The inventory, at a minimum, must contain department owner, review date, and purpose. Perform service account reviews to validate that all active accounts are authorized, on a recurring schedule at a minimum quarterly, or more frequently.		x	x
v7	3.3 Protect Dedicated Assessment Accounts - Use a dedicated account for authenticated vulnerability scans, which should not be used for any other administrative activities and should be tied to specific machines at specific IP addresses.