cis-eks-v180-4-1-11

name	cis-eks-v180-4.1.11
description	Minimize access to webhook configuration objects (Manual)
category	cis-eks
version	1.8.0
author	cyberstrike-official
tags	["cis","eks","kubernetes","aws","rbac","webhooks","admission-control"]
cis_id	4.1.11
cis_benchmark	CIS Amazon Elastic Kubernetes Service (EKS) Benchmark v1.8.0
tech_stack	["kubernetes","aws","eks"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

4.1.11 Minimize access to webhook configuration objects (Manual)

Profile Applicability

• Level 1

Description

Users with rights to create/modify/delete validatingwebhookconfigurations or mutatingwebhookconfigurations can control webhooks that can read any object admitted to the cluster, and in the case of mutating webhooks, also mutate admitted objects. This could allow for privilege escalation or disruption of the operation of the cluster.

Rationale

The ability to manage webhook configuration should be limited.

Audit Procedure

Review the users who have access to validatingwebhookconfigurations or mutatingwebhookconfigurations objects in the Kubernetes API.

kubectl get clusterroles -o json | jq -r '.items[] | select(.rules[]? | select(.resources[]? == "validatingwebhookconfigurations" or .resources[]? == "mutatingwebhookconfigurations")) | .metadata.name'

Remediation

Where possible, remove access to the validatingwebhookconfigurations or mutatingwebhookconfigurations objects.

Default Value

By default, the cluster-admin ClusterRole has access to webhook configuration objects.

References

1. https://kubernetes.io/docs/concepts/security/rbac-good-practices/#control-admission-webhooks

CIS Controls

Controls Version	Control	IG 1	IG 2	IG 3
v8	6.8 Define and Maintain Role-Based Access Control			●

Profile Applicability

• Level 1