cis-docker-5-7

name	cis-docker-5.7
description	Ensure sshd is not run within containers
category	cis-docker
version	1.8.0
author	cyberstrike-official
tags	["cis","docker","linux","containers","runtime","ssh","security"]
cis_id	5.7
cis_benchmark	CIS Docker Benchmark v1.8.0
tech_stack	["linux","docker"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

5.7 Ensure sshd is not run within containers (Manual)

Profile Applicability

• Level 1 - Docker - Linux

Description

The SSH daemon should not be running within the container. You should SSH into the Docker host, and use docker exec to enter a container.

Rationale

Running SSH within the container increases the complexity of security management by making it

• Difficult to manage access policies and security compliance for SSH server
• Difficult to manage keys and passwords across various containers
• Difficult to manage security upgrades for SSH server

It is possible to have shell access to a container without using SSH, the needlessly increasing the complexity of security management should be avoided.

Impact

None.

Audit Procedure

List all the running instances of containers by executing below command:

docker ps --quiet

For each container instance, execute the below command:

docker exec <CONTAINER_ID> ps -el

Ensure that there is no process for SSH server.

Remediation

Uninstall the SSH daemon from the container and use and use docker exec to enter a container on the remote host.

docker exec --interactive --tty <CONTAINER_ID> sh

OR

docker attach <CONTAINER_ID>

Default Value

By default, SSH server is not running inside the container. Only one process per container is allowed.

References

1. https://jpetazzo.github.io/2014/06/23/docker-ssh-considered-evil/

CIS Controls

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.

v7

9.2 Ensure Only Approved Ports, Protocols and Services Are Running

Ensure that only network ports, protocols, and services listening on a system with validated business needs, are running on each system.