Cis Ocp V160 1.2.27

CIS Red Hat OpenShift Container Platform Benchmark v1.6.0 - Control 1.2.27

Profile Applicability

• Level: 1

Description

etcd should be configured to make use of TLS encryption for client connections.

Rationale

etcd is a highly-available key value store used by Kubernetes deployments for persistent storage of all of its REST API objects. These objects are sensitive in nature and should be protected by client authentication. This requires the API server to identify itself to the etcd server using a client certificate and key.

Impact

TLS and client certificate authentication are configured by default for etcd.

Audit Procedure

OpenShift uses X.509 certificates to provide secure communication to etcd. OpenShift configures these automatically. OpenShift does not use the etcd-certfile or etcd-keyfile flags. Certificates are used for encrypted communication between etcd member peers, as well as encrypted client traffic. The following certificates are generated and used by etcd and other processes that communicate with etcd:

• Peer certificates: Used for communication between etcd members.
• Client certificates: Used for encrypted server-client communication. Client certificates are currently used by the API server only, and no other service should connect to etcd directly except for the proxy. Client secrets (etcd-client, etcd-metric-client, etcd-metric-signer, and etcd-signer) are added to the openshift-config, openshift-monitoring, and openshift-kube-apiserver namespaces.
• Server certificates: Used by the etcd server for authenticating client requests.
• Metric certificates: All metric consumers connect to proxy with metric-client certificates.

Run the following command to check the location of the etcd-certfile:

oc get configmap config -n openshift-kube-apiserver -ojson | \
  jq -r '.data["config.yaml"]' | \
  jq -r '.apiServerArguments["etcd-certfile"]'

Verify that /etc/kubernetes/static-pod-resources/secrets/etcd-client/tls.crt is returned.

Run the following command to check the location of the etcd-keyfile:

oc get configmap config -n openshift-kube-apiserver -ojson | \
  jq -r '.data["config.yaml"]' | \
  jq -r '.apiServerArguments["etcd-keyfile"]'

Verify that /etc/kubernetes/static-pod-resources/secrets/etcd-client/tls.key is returned.

Remediation

OpenShift automatically manages TLS and client certificate authentication for etcd. This is not configurable.

Default Value

By default, OpenShift uses X.509 certificates to provide secure communication to etcd. OpenShift configures these automatically. OpenShift does not use the etcd-certfile or etcd-keyfile flags. OpenShift generates the necessary files and sets the arguments appropriately.

References

1. https://docs.openshift.com/container-platform/latest/security/certificate_types_descriptions/etcd-certificates.html
2. https://kubernetes.io/docs/reference/command-line-tools-reference/kube-apiserver/
3. https://etcd.io/

CIS Controls

MITRE ATT&CK Mappings

Profile

Level 1 (Manual)