CIS-1.2.24 - Ensure that the API Server --service-account-key-file argument is set as appropriate

Ensure that the API Server --service-account-key-file argument is set as appropriate

Framework

CIS

Severity

Medium

Description of the the issue

By default, if no --service-account-key-file is specified to the apiserver, it uses the private key from the TLS serving certificate to verify service account tokens. To ensure that the keys for service account tokens could be rotated as needed, a separate public/private key pair should be used for signing service account tokens. Hence, the public key should be specified to the apiserver with --service-account-key-file.

Related resources

What does this control test

Explicitly set a service account public key file for service accounts on the apiserver.

How to check it manually

Run the following command on the Control Plane node:

ps -ef | grep kube-apiserver

Verify that the --service-account-key-file argument exists and is set as appropriate.

Remediation

Edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the Control Plane node and set the --service-account-key-file parameter to the public key file for service accounts:

--service-account-key-file=<filename>

Impact Statement

The corresponding private key must be provided to the controller manager. You would need to securely maintain the key file and rotate the keys based on your organization's key rotation policy.

Default Value

By default, --service-account-key-file argument is not set.

Example

No example