Pods should verify the API server's serving certificate before connecting
Set up the kubernetes integration.
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.
Audit
Run the following command on the master 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.
Edit the Controller Manager pod specification file /etc/kubernetes/manifests/kube-controller-manager.yaml on the master node and set the --root-ca-file parameter to the certificate bundle file: --root-ca-file=<path/to/file>
Impact
You need to setup and maintain root certificate authority file.
Default value
By default, --root-ca-file is not set.
References
- https://kubernetes.io/docs/admin/kube-controller-manager/
- https://github.com/kubernetes/kubernetes/issues/11000
CIS controls
Version 6 14.2 Encrypt All Sensitive Information Over Less-trusted Networks All communication of sensitive information over less-trusted networks should be encrypted. Whenever information flows over a network with a lower trust level, the information should be encrypted.
Version 7 14.4 Encrypt All Sensitive Information in Transit Encrypt all sensitive information in transit.
