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

Information

Enable Kubelet authentication using certificates.

Rationale:

The connections from the apiserver to the kubelet are used for fetching logs for pods, attaching (through kubectl) to running pods, and using the kubelet's port-forwarding functionality. These connections terminate at the kubelet's HTTPS endpoint. By default, the apiserver does not verify the kubelet's serving certificate, which makes the connection subject to man-in-the-middle attacks, and unsafe to run over untrusted and/or public networks. Enabling Kubelet certificate authentication ensures that the apiserver could authenticate the Kubelet before submitting any requests.

Impact:

You require TLS to be configured on apiserver as well as kubelets.

NOTE: Nessus has not performed this check. Please review the benchmark to ensure target compliance.

Solution

None. Changing the clientCAFile value is unsupported.

Default Value:

By default, the clientCAFile is set to /etc/kubernetes/kubelet-ca.crt.

See Also

https://workbench.cisecurity.org/benchmarks/14166