The Kubernetes API server must use approved cipher suites.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-242418	CNTR-K8-001400	SV-242418r961110_rule		Medium

Description

The Kubernetes API server communicates to the kubelet service on the nodes to deploy, update, and delete resources. If an attacker were able to get between this communication and modify the request, the Kubernetes cluster could be compromised. Using approved cypher suites for the communication ensures the protection of the transmitted information, confidentiality, and integrity so that the attacker cannot read or alter this communication.

STIG	Date
Kubernetes Security Technical Implementation Guide	2024-08-22

Details

Check Text (C-45693r863842_chk)

Change to the /etc/kubernetes/manifests/ directory on the Kubernetes Control Plane. Run the command:
grep -i tls-cipher-suites *

If the setting feature tls-cipher-suites is not set in the Kubernetes API server manifest file or contains no value or does not contain TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384, this is a finding.

Fix Text (F-45651r927105_fix)

Edit the Kubernetes API Server manifest file in the /etc/kubernetes/manifests directory on the Kubernetes Control Plane.

Set the value of "--tls-cipher-suites" to:
"TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384"