A flaw was found in the Application Subscription controller (multicluster-operators-subscription) of Red Hat Advanced Cluster Management for Kubernetes (ACM). A user with namespace-scoped edit privileges in an ACM hub namespace can create a Channel resource pointing to a Helm repository they control and a Subscription resource referencing it. The app-subscription controller fetches and applies the Helm chart contents with its own elevated authority, without verifying whether the subscription creator holds the open-cluster-management:subscription-admin role and without restricting applied resources to the subscription namespace. This allows the attacker to include cluster-scoped resources in the Helm chart, such as a ClusterRoleBinding granting the attackers ServiceAccount the cluster-admin ClusterRole. Successful exploitation results in full cluster-admin privilege escalation. This contradicts the ACM documentation which states that non-subscription-admin users should have resources deployed into the subscription namespace only.
Weakness
A particular privilege, role, capability, or right can be used to perform unsafe actions that were not intended, even when it is assigned to the correct entity.
Potential Mitigations
Related Attack Patterns
- https://cwe.mitre.org/data/definitions/58.html
- https://cwe.mitre.org/data/definitions/634.html
- https://cwe.mitre.org/data/definitions/637.html
- https://cwe.mitre.org/data/definitions/643.html
- https://cwe.mitre.org/data/definitions/648.html