CIS-5.2.3 - Minimize the admission of containers wishing to share the host process ID namespace

Minimize the admission of containers wishing to share the host process ID namespace

Framework

CIS

Severity

Medium

Description of the the issue

A container running in the host's PID namespace can inspect processes running outside the container. If the container also has access to ptrace capabilities this can be used to escalate privileges outside of the container.

There should be at least one admission control policy defined which does not permit containers to share the host PID namespace.

If you need to run containers which require hostPID, this should be defined in a separate policy and you should carefully check to ensure that only limited service accounts and users are given permission to use that policy.

Related resources

MutatingWebhookConfiguration, Namespace, ValidatingWebhookConfiguration

What does this control test

Do not generally permit containers to be run with the hostPID flag set to true.

How to check it manually

List the policies in use for each namespace in the cluster, ensure that each policy disallows the admission of hostPID containers

Remediation

Add policies to each namespace in the cluster which has user workloads to restrict the admission of hostPID containers.

Impact Statement

Pods defined with spec.hostPID: true will not be permitted unless they are run under a specific policy.

Default Value

By default, there are no restrictions on the creation of hostPID containers.

Example

No example