cis-k8s-v1120-5-2-3

name	cis-k8s-v1120-5.2.3
description	Minimize the admission of containers wishing to share the host process ID namespace (Manual)
category	cis-k8s
version	1.12.0
author	cyberstrike-official
tags	["cis","kubernetes","policies","pod-security"]
cis_id	5.2.3
cis_benchmark	CIS Kubernetes Benchmark v1.12.0
tech_stack	["kubernetes"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

5.2.3 Minimize the admission of containers wishing to share the host process ID namespace (Manual)

Profile Applicability

• Level 1 - Master Node

Description

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

Rationale

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.

Impact

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

Audit Procedure

Fetch hostPID from each pod with:

kubectl get pods -A -o=jsonpath=$'{range .items[*]}{@.metadata.name}: {@.spec.hostPID}\n{end}'

Remediation

Configure the Admission Controller to restrict the admission of hostPID containers.

Default Value

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

References

1. https://kubernetes.io/docs/concepts/security/pod-security-standards/

CIS Controls

Controls Version	Control	IG 1	IG 2	IG 3
v8	13.10 Perform Application Layer Filtering			X
v7	12.9 Deploy Application Layer Filtering Proxy Server			X