cis-docker-v170-2-6

name	cis-docker-v170-2.6
description	Ensure aufs storage driver is not used
category	cis-docker
version	1.7.0
author	cyberstrike-official
tags	["cis","docker","daemon","configuration","storage","aufs","overlay2"]
cis_id	2.6
cis_benchmark	CIS Docker Benchmark v1.7.0
tech_stack	["docker"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

CIS Docker Benchmark v1.7.0 - Control 2.6

Profile Applicability

• Level: 1 - Docker - Linux

Description

Do not use aufs as the storage driver for your Docker instance.

Rationale

The aufs storage driver is the oldest storage driver used on Linux systems. It is based on a Linux kernel patch-set that is unlikely in future to be merged into the main OS kernel. The aufs driver is also known to cause some serious kernel crashes. aufs only has legacy support within systems using Docker.

Most importantly, aufs is not a supported driver in many Linux distributions using latest Linux kernels and has also been deprecated with Docker Engine release 20.10.

Impact

aufs is the only storage driver that allows containers to share executable and shared library memory. It might be useful if you are running thousands of containers with the same program or libraries, however its use should be reviewed in line with your organization's security policy.

Audit Procedure

Execute the below command and verify that aufs is not used as storage driver:

docker info --format 'Storage Driver: {{ .Driver }}'

The above command should not return aufs.

Remediation

Do not explicitly use aufs as storage driver.

For example, do not start Docker daemon as below:

dockerd --storage-driver aufs

Default Value

By default, Docker uses overlay2 as the storage driver on most of the platforms. The default storage driver can vary based on your OS vendor. You should use the storage driver that is recommended by your preferred vendor and which is in line with policy around the applications which are being deployed.

References

1. https://docs.docker.com/storage/storagedriver/select-storage-driver/

CIS Controls

Controls Version	Control	IG 1	IG 2	IG 3
v8	16 Application Software Security Manage the security life cycle of in-house developed, hosted, or acquired software to prevent, detect, and remediate security weaknesses before they can impact the enterprise.