Cis Ocp V190 1.2.3

CIS Red Hat OpenShift Container Platform Benchmark v1.9.0 - Control 1.2.3

Profile Applicability

• Level: 1

Description

Enable certificate based kubelet authentication.

Rationale

The apiserver, by default, does not authenticate itself to the kubelet's HTTPS endpoints. The requests from the apiserver are treated anonymously. You should set up certificate-based kubelet authentication to ensure that the apiserver authenticates itself to kubelets when submitting requests.

Impact

Require TLS to be configured on the apiserver as well as kubelets.

Audit Procedure

OpenShift does not use the --kubelet-client-certificate or the kubelet-client-key arguments. OpenShift utilizes X.509 certificates for authentication of the control-plane components. OpenShift configures the API server to use an internal certificate authority (CA) to validate the user certificate sent during TLS negotiation. If the CA validation of the certificate is successful, the request is authenticated and user information is derived from the certificate subject fields.

To verify the certificates are present, run the following command:

#for OpenShift 4.6 and above
oc get configmap config -n openshift-kube-apiserver -ojson | jq -r '.data["config.yaml"]' | jq '.apiServerArguments["kubelet-client-certificate"]'

oc get configmap config -n openshift-kube-apiserver -ojson | jq -r '.data["config.yaml"]' | jq '.apiServerArguments["kubelet-client-key"]'

oc -n openshift-kube-apiserver describe secret serving-cert

Verify that the kubelet client-certificate and kubelet client-key files are present.

client-certificate: /etc/kubernetes/static-pod-certs/secrets/kubelet-client/tls.crt

client-key: /etc/kubernetes/static-pod-certs/secrets/kubelet-client/tls.key

Verify that the serving-cert for the openshift-apiserver is type kubernetes.io/tls and that returned Data includes tls.crt and tls.key.

Remediation

No remediation is required. OpenShift platform components use X.509 certificates for authentication. OpenShift manages the CAs and certificates for platform components. This is not configurable.

Default Value

By default, kubelet authentication is managed with X.509 certificates.

References

1. https://github.com/openshift/cluster-kube-apiserver-operator/blob/release-4.13/bindata/assets/config/defaultconfig.yaml#L124-L127
2. https://kubernetes.io/docs/admin/kube-apiserver/
3. https://kubernetes.io/docs/reference/command-line-tools-reference/kubelet-authentication-authorization/
4. https://kubernetes.io/docs/concepts/architecture/control-plane-node-communication/
5. https://docs.openshift.com/container-platform/4.13/operators/operator-reference.html#kube-apiserver-operator_red-hat-operators
6. https://docs.openshift.com/container-platform/4.13/operators/operator-reference.html#openshift-apiserver-operator_red-hat-operators

CIS Controls

MITRE ATT&CK Mappings

Profile

Level 1 (Manual)