GMS-2023-1177: A potential risk in clusternet which can be leveraged to make a cluster-level privilege escalation

Summary:

A potential risk in clusternet which can be leveraged to make a cluster-level privilege escalation.

Detailed analysis:

The clusternet has a deployment called cluster-hub inside the clusternet-system Kubernetes namespace, which runs on worker nodes randomly. The deployment has a service account called clusternet-hub, which has a cluster role called clusternet:hub via cluster role binding. The clusternet:hub cluster role has “” verbs of “.*” resources. Thus, if a malicious user can access the worker node which runs the clusternet, he/she can leverage the service account to do malicious actions to critical system resources. For example, he/she can leverage the service account to get ALL secrets in the entire cluster, resulting in cluster-level privilege escalation.