Profile applicability: Level 1
Kubernetes Roles and ClusterRoles provide access to resources based on sets of objects
and actions that can be taken on those objects. It is possible to set either of these
to be the wildcard "*", which matches all items.
Use of wildcards is not optimal from a security perspective as it may allow for inadvertent
access to be granted when new resources are added to the Kubernetes API either as
CRDs or in later versions of the product.
The principle of least privilege recommends that users are provided only the access
required for their role and nothing more. The use of wildcard rights grants is likely
to provide excessive rights to the Kubernetes API.
Audit
Retrieve the roles defined across each namespaces in the cluster and review for wildcards.
Here’s a null-safe, column-formatted command that shows only Roles and ClusterRoles
that use a wildcard (*) anywhere in verbs, resources, or apiGroups—and tells you which
field(s) use the wildcard:
kubectl get clusterrole,role -A -o json | jq -r ' def has_star(a): (a // []) | any(. == "*");
.items[] | . as $r |
( any($r.rules[]?; has_star(.verbs)) ) as $wv |
( any($r.rules[]?; has_star(.resources)) ) as $wr |
( any($r.rules[]?; has_star(.apiGroups)) ) as $wg |
select($wv or $wr or $wg) |
[ $r.kind, $r.metadata.name,
($r.metadata.namespace // "cluster-wide"),
([ if $wv then "verbs" else empty end,
if $wr then "resources" else empty end,
if $wg then "apiGroups" else empty end
] | join(","))
] | @tsv
' | awk -F'\t' '{printf "%-15s %-40s %-20s %-20s\n", $1, $2, $3, $4}'
Sample Output from command:
KIND NAME NAMESPACE WILDCARD_IN --------------- ---------------------------------------- -------------------- -------------------- ClusterRole cluster-admin cluster-wide verbs,resources,apiGroups ClusterRole external-metrics-reader cluster-wide resources ClusterRole kubelet-api-admin cluster-wide verbs ClusterRole system:cloud-controller-manager cluster-wide resources,apiGroups ClusterRole system:controller:disruption-controller cluster-wide apiGroups ClusterRole system:controller:generic-garbage-collector cluster-wide resources,apiGroups ClusterRole system:controller:horizontal-pod-autoscaler cluster-wide resources,apiGroups ClusterRole system:controller:namespace-controller cluster-wide resources,apiGroups ClusterRole system:controller:resourcequota-controller cluster-wide resources,apiGroups ClusterRole system:gcp-controller-manager cluster-wide verbs ClusterRole system:gke-common-webhooks cluster-wide verbs,resources,apiGroups ClusterRole system:gke-hpa-actor cluster-wide resources,apiGroups ClusterRole system:glbc-status cluster-wide verbs ClusterRole system:kube-controller-manager cluster-wide resources,apiGroups ClusterRole system:kubelet-api-admin cluster-wide verbs ClusterRole system:kubestore-collector cluster-wide verbs,resources,apiGroups ClusterRole system:managed-certificate-controller cluster-wide verbs ClusterRole system:metrics-server-nanny cluster-wide verbs Role gke-spiffe-leaderelection kube-system verbs
Remediation
Where possible replace any use of wildcards in clusterroles and roles with specific
objects or actions.