C-0063 - Portforwarding privileges

Portforwarding privileges

Framework

ArmoBest

Description of the the issue

Attackers who have relevant RBAC permissions, can run open a backdoor communication channel directly to the sockets inside target container using exec command “kubectl portforward” command. Using this method, attackers can bypass network security restrictions and communicate directly with software in the containers.

Related resources

ClusterRole, ClusterRoleBinding, Role, RoleBinding

What does this control test

Check which subjects have RBAC permissions to portforward into pods– if they have the “pods/portforward” resource.

Remediation

It is recommended to prohibit “kubectl portforward” command in production environments. It is also recommended not to use subjects with this permission for daily cluster operations.

Example

kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  namespace: my-namespace
  name: allow-port-forward
rules:
- apiGroups: [""]
  resources: ["pods", "pods/portforward"] # we look for this resource or *
  verbs: ["get", "list", "create"]    # we look for these verbs or *

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