cyberstrikeus 5.1.2 Minimize access to secrets (Manual)
Profile Applicability
- Level 1 - Master Node
Description
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.
Rationale
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.
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, restrict access to secret objects in the cluster by removing get, list, and watch permissions.
Default Value
By default in a kubeadm cluster the following list of principals have get privileges on secret objects:
| CLUSTERROLEBINDING | SUBJECT |
|---|---|
| cluster-admin (Group) | system:masters |
| system:controller:clusterrole-aggregation-controller (ServiceAccount, kube-system) | clusterrole-aggregation-controller |
| system:controller:expand-controller (ServiceAccount, kube-system) | expand-controller |
| system:controller:generic-garbage-collector (ServiceAccount, kube-system) | generic-garbage-collector |
| system:controller:namespace-controller (ServiceAccount, kube-system) | namespace-controller |
| system:controller:persistent-volume-binder (ServiceAccount, kube-system) | persistent-volume-binder |
| system:kube-controller-manager (User) | system:kube-controller-manager |