Assessing Kubernetes RBAC: Methodologies and Pitfalls // DaemonCore Field Notes

// Understanding RBAC in Kubernetes

Kubernetes Role-Based Access Control (RBAC) is a critical mechanism for managing permissions within the cluster. However, misconfigured RBAC policies can expose your environment to unwanted access and potential breaches. A systematic assessment of RBAC configurations can identify over-permissions, misalignments, and other vulnerabilities.

// Methodology for Assessing RBAC

1. Inventory Current RBAC Policies Start by exporting the existing RBAC policies for analysis. Use the following command:

   kubectl get roles --all-namespaces -o yaml > roles.yaml
   kubectl get rolebindings --all-namespaces -o yaml > rolebindings.yaml
   kubectl get clusterroles -o yaml > clusterroles.yaml
   kubectl get clusterrolebindings -o yaml > clusterrolebindings.yaml

This collection gives a complete view of role and binding configurations.

2. Analyze Role Permissions Review the roles and bindings to identify any excessive permissions. It’s crucial to check both Roles and ClusterRoles to understand the scope of access. For instance, the following YAML indicates a role that might be overly permissive:

   apiVersion: rbac.authorization.k8s.io/v1
   kind: Role
   metadata:
     namespace: default
     name: developer-role
   rules:
     - apiGroups: ["*"]  # This is too broad
       resources: ["*"]  # Also overly open
       verbs: ["*"]      # Full control

Roles should follow the principle of least privilege.

3. Use Tools for Analysis Employ tools such as kube-score or kubeaudit to help identify risky RBAC configurations. For example, run:

   kubeaudit rbac

This command will help find common RBAC misconfigurations, providing suggestions for remediation.

4. Simulate Role Requests Create test scenarios that simulate API requests using the permissions defined in your RBAC. This can be done using kubectl auth can-i. For example, check if a role has permission to list pods:

   kubectl auth can-i list pods --as=<service-account> --namespace=<namespace>

Adjust <service-account> and <namespace> accordingly to run tests against specific roles.

5. Document Findings and Remediation Steps Keep detailed records of your findings, including which roles are overly permissive and recommendations for tightening access. A good practice is to create a remediation checklist:

- [ ] Identify roles with `apiGroups: [