cis-k8s-v1120-1-2-10

name	cis-k8s-v1120-1.2.10
description	Ensure that the admission control plugin AlwaysAdmit is not set (Automated)
category	cis-k8s
version	1.12.0
author	cyberstrike-official
tags	["cis","kubernetes","control-plane","api-server","admission-control","always-admit"]
cis_id	1.2.10
cis_benchmark	CIS Kubernetes Benchmark v1.12.0
tech_stack	["kubernetes"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

1.2.10 Ensure that the admission control plugin AlwaysAdmit is not set (Automated)

Profile Applicability

• Level 1 - Master Node

Description

Do not allow all requests.

Rationale

Setting admission control plugin AlwaysAdmit allows all requests and do not filter any requests.

The AlwaysAdmit admission controller was deprecated in Kubernetes v1.13. Its behavior was equivalent to turning off all admission controllers.

Impact

Only requests explicitly allowed by the admissions control plugins would be served.

Audit

Run the following command on the Control Plane node:

ps -ef | grep kube-apiserver

Verify that if the --enable-admission-plugins argument is set, its value does not include AlwaysAdmit.

Remediation

Edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the Control Plane node and either remove the --enable-admission-plugins parameter, or set it to a value that does not include AlwaysAdmit.

Default Value

AlwaysAdmit is not in the list of default admission plugins.

References

1. https://kubernetes.io/docs/reference/command-line-tools-reference/kube-apiserver/
2. https://kubernetes.io/docs/reference/access-authn-authz/admission-controllers/#alwaysadmit

CIS Controls

Controls Version	Control	IG 1	IG 2	IG 3
v8	3.3 Configure Data Access Control Lists	*	*	*
v7	14.6 Protect Information through Access Control Lists	*	*	*