Views:
Profile applicability: Level 1
The Kubernetes API stores secrets, which may be service account tokens for the Kubernetes API or credentials used by workloads in the cluster. Access to these secrets should be restricted to the smallest possible group of users to reduce the risk of privilege escalation.
Inappropriate access to secrets stored within the Kubernetes cluster can allow for an attacker to gain additional access to the Kubernetes cluster or external resources whose credentials are stored as secrets.
Note
Note
By default, the following list of principals have get privileges on secret objects: 
CLUSTERROLEBINDING                                     SUBJECT
TYPE                     SA-NAMESPACE
cluster-admin                                                   system:masters
Group
system:controller:clusterrole-aggregation-controller            clusterrole-
aggregation-controller ServiceAccount kube-system
system:controller:expand-controller                             expand-controller
ServiceAccount kube-system
system:controller:generic-garbage-collector                     generic-garbage-
collector ServiceAccount kube-system
system:controller:namespace-controller                          namespace-controller
ServiceAccount kube-system
system:controller:persistent-volume-binder                      persistent-volume-
binder ServiceAccount kube-system
system:kube-controller-manager                                  system:kube-controller-
manager User

Impact

Care should be taken not to remove access to secrets to system components which require this for their operation.

Audit

Review the users who have get, list or watch access to secrets objects in the Kubernetes API.

Remediation

Where possible, remove get, list and watch access to secret objects in the cluster.