Cis K8S V1120 1.3.6

CIS Kubernetes Benchmark v1.12.0 - Control 1.3.6

Profile Applicability

• Level: 1 - Master Node

Description

Enable kubelet server certificate rotation on controller-manager.

Rationale

RotateKubeletServerCertificate causes the kubelet to both request a serving certificate after bootstrapping its client credentials and rotate the certificate as its existing credentials expire. This automated periodic rotation ensures that the there are no downtimes due to expired certificates and thus addressing availability in the CIA security triad.

Note: This recommendation only applies if you let kubelets get their certificates from the API server. In case your kubelet certificates come from an outside authority/tool (e.g. Vault) then you need to take care of rotation yourself.

Impact

None

Audit Procedure

Run the following command on the Control Plane node:

ps -ef | grep kube-controller-manager

Verify that RotateKubeletServerCertificate argument exists and is set to true.

Remediation

Edit the Controller Manager pod specification file /etc/kubernetes/manifests/kube-controller-manager.yaml on the Control Plane node and set the --feature-gates parameter to include RotateKubeletServerCertificate=true.

--feature-gates=RotateKubeletServerCertificate=true

Default Value

By default, RotateKubeletServerCertificate is set to "true" this recommendation verifies that it has not been disabled.

References

1. https://kubernetes.io/docs/admin/kubelet-tls-bootstrapping/#approval-controller
2. https://github.com/kubernetes/features/issues/267
3. https://github.com/kubernetes/kubernetes/pull/45059
4. https://kubernetes.io/docs/admin/kube-controller-manager/

CIS Controls

Profile

Level 1 - Master Node (Automated)