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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.
Default value:
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.