Cis Eks V180 4.1.9

4.1.9 Minimize access to create persistent volumes (Manual)

Profile Applicability

• Level 1

Description

The ability to create persistent volumes in a cluster can provide an opportunity for privilege escalation, via the creation of hostPath volumes. As persistent volumes are not covered by Pod Security Admission, a user with access to create persistent volumes may be able to get access to sensitive files from the underlying host even where restrictive Pod Security Admission policies are in place.

Rationale

The ability to create persistent volumes in a cluster opens up possibilities for privilege escalation and should be restricted, where possible.

Audit Procedure

Review the users who have create access to PersistentVolume objects in the Kubernetes API.

kubectl get clusterrolebindings -o json | jq -r '.items[] | select(.roleRef.kind=="ClusterRole") | select(.subjects[]?.kind=="User" or .subjects[]?.kind=="Group" or .subjects[]?.kind=="ServiceAccount") | .metadata.name + " -> " + .roleRef.name'

Remediation

Where possible, remove create access to PersistentVolume objects in the cluster.

Default Value

By default, the cluster-admin ClusterRole has access to create PersistentVolume objects.

References

1. https://kubernetes.io/docs/concepts/security/rbac-good-practices/#persistent-volume-creation

CIS Controls

Profile Applicability

• Level 1