CIS-1.2.27 - Ensure that the API Server --client-ca-file argument is set as appropriate

Ensure that the API Server --client-ca-file argument is set as appropriate

Framework

CIS

Severity

High

Description of the the issue

API server communication contains sensitive parameters that should remain encrypted in transit. Configure the API server to serve only HTTPS traffic. If --client-ca-file argument is set, any request presenting a client certificate signed by one of the authorities in the client-ca-file is authenticated with an identity corresponding to the CommonName of the client certificate.

Related resources

Pod

What does this control test

Setup TLS connection on the API server.

How to check it manually

Run the following command on the Control Plane node:

ps -ef | grep kube-apiserver

Verify that the --client-ca-file argument exists and it is set as appropriate.

Remediation

Follow the Kubernetes documentation and set up the TLS connection on the apiserver. Then, edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the client certificate authority file.

--client-ca-file=<path/to/client-ca-file>

Impact Statement

TLS and client certificate authentication must be configured for your Kubernetes cluster deployment.

Default Value

By default, --client-ca-file argument is not set.

Example

No example