Cis K8S V1111 1.3.5

1.3.5 Ensure that the --root-ca-file argument is set as appropriate (Automated)

Profile Applicability

• Level 1 - Master Node

Description

Allow pods to verify the API server's serving certificate before establishing connections.

Rationale

Processes running within pods that need to contact the API server must verify the API server's serving certificate. Failing to do so could be a subject to man-in-the-middle attacks.

Providing the root certificate for the API server's serving certificate to the controller manager with the --root-ca-file argument allows the controller manager to inject the trusted bundle into pods so that they can verify TLS connections to the API server.

Impact

You need to setup and maintain root certificate authority file.

Audit

Run the following command on the Control Plane node:

ps -ef | grep kube-controller-manager

Verify that the --root-ca-file argument exists and is set to a certificate bundle file containing the root certificate for the API server's serving certificate.

Remediation

Edit the Controller Manager pod specification file /etc/kubernetes/manifests/kube-controller-manager.yaml on the Control Plane node and set the --root-ca-file parameter to the certificate bundle file.

--root-ca-file=<path/to/file>

Default Value

By default, --root-ca-file is not set.

References

1. https://kubernetes.io/docs/admin/kube-controller-manager/
2. https://github.com/kubernetes/kubernetes/issues/11000

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