Details
Validate service account before validating token.
Rationale:
If –service-account-lookup is not enabled, the apiserver only verifies that the authentication token is valid, and does not validate that the service account token mentioned in the request is actually present in etcd. This allows using a service account token even after the corresponding service account is deleted. This is an example of time of check to time of use security issue.
Impact:
None
Solution
Edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the below parameter.
–service-account-lookup=true
Alternatively, you can delete the –service-account-lookup parameter from this file so that the default takes effect.
Default Value:
By default, –service-account-lookup argument is set to true.
Supportive Information
The following resource is also helpful.
This security hardening control applies to the following category of controls within NIST 800-53: Identification and Authentication.This control applies to the following type of system Unix.