Cis Ocp V190 4.2.10

CIS Red Hat OpenShift Container Platform Benchmark v1.9.0 - Control 4.2.10

Profile Applicability

• Level: 2

Description

Enable kubelet client certificate rotation.

Rationale

The --rotate-certificates setting causes the kubelet to rotate its client certificates by creating new CSRs as its existing credentials expire. This automated periodic rotation ensures that the there is no downtime 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

This feature also requires the RotateKubeletClientCertificate feature gate to be enabled. The feature gate is enabled by default.

Run the following command to check that certificate rotation is enabled for each node:

for node in $(oc get nodes -ojsonpath='{.items[*].metadata.name}'); do
oc get --raw /api/v1/nodes/$node/proxy/configz | jq '.kubeletconfig.rotateCertificates'
done

Verify all the nodes return true.

Remediation

None.

Default Value

By default, in OpenShift 4, kubelet client certificate rotation is enabled.

References

1. https://docs.openshift.com/container-platform/latest/architecture/control-plane.html#understanding-machine-config-operator_control-plane
2. https://github.com/openshift/kubernetes-kubelet/blob/origin-4.5-kubernetes-1.18.3/config/v1beta1/types.go#L172-L181
3. https://github.com/openshift/machine-config-operator/blob/release-4.5/templates/master/01-master-kubelet/_base/files/kubelet.yaml
4. https://github.com/openshift/machine-config-operator/blob/release-4.5/templates/worker/01-worker-kubelet/_base/files/kubelet.yaml
5. https://github.com/kubernetes/kubernetes/pull/41912
6. https://kubernetes.io/docs/reference/command-line-tools-reference/kubelet-tls-bootstrapping/#kubelet-configuration
7. https://kubernetes.io/docs/imported/release/notes/
8. https://kubernetes.io/docs/reference/command-line-tools-reference/feature-gates/

CIS Controls

MITRE ATT&CK Mappings

Profile

Level 2 (Manual)