cis-ocp-v170-4-2-12

name	cis-ocp-v170-4.2.12
description	Ensure that the Kubelet only makes use of Strong Cryptographic Ciphers (Manual)
category	cis-openshift
version	1.7.0
author	cyberstrike-official
tags	["cis","openshift","kubernetes","redhat","worker-node","kubelet"]
cis_id	4.2.12
cis_benchmark	CIS Red Hat OpenShift Container Platform Benchmark v1.7.0
tech_stack	["kubernetes","openshift","redhat"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

CIS Red Hat OpenShift Container Platform Benchmark v1.7.0 - Control 4.2.12

Profile Applicability

• Level: 1

Description

Ensure that the Kubelet is configured to only use strong cryptographic ciphers.

Rationale

TLS ciphers have had a number of known vulnerabilities and weaknesses, which can reduce the protection provided by them. By default Kubernetes supports a number of TLS ciphersuites including some that have security concerns, weakening the protection provided.

Impact

Kubelet clients that cannot support modern cryptographic ciphers will not be able to make connections to the Kubelet API.

Audit Procedure

The set of cryptographic ciphers currently considered secure is the following:

TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256
TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305
TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305
TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384
TLS_RSA_WITH_AES_256_GCM_SHA384
TLS_RSA_WITH_AES_128_GCM_SHA256

Ciphers for the API servers, authentication and the ingress controller can be configured using the tlsSecurityProfile parameter as of OpenShift 4.3. The ingress controller provides external access to the API server. There are four TLS security profile types:

• Old
• Intermediate
• Modern
• Custom

Only the Old, Intermediate and Custom profiles are supported at this time for the Ingress controller. Custom provides the ability to specify individual TLS security profile parameters. Follow the steps in the documentation to configure the cipher suite for Ingress, API server and Authentication: https://docs.openshift.com/container-platform/4.5/networking/ingress-operator.html#nw-ingress-controller-configuration-parameters_configuring-ingress

Run the following commands to verify the cipher suite and minTLSversion for the ingress operator, authentication operator, cliconfig, OpenShift APIserver and Kube APIserver.

Use the following command to verify the available ciphers:

oc get --namespace=openshift-ingress-operator ingresscontroller/default -ojson | jq .status.tlsProfile.ciphers

Verify the ciphers used by the Kubernetes API server:

oc get kubeapiservers.operator.openshift.io cluster -ojson | jq .spec.observedConfig.servingInfo.cipherSuites