☸️CIS Kubernetes 5.1.6Rule: K8S-RBAC-006critical

Cluster-admin restricted

Description

ClusterRoleBindings to cluster-admin should be restricted to limited identities (cluster operators only).

⚠️ Risk Impact

cluster-admin is full K8s superuser. Granted broadly = single-credential-compromise gives total cluster control.

🔍 How EchelonGraph Detects This

K8S-RBAC-006Automated scanner rule

EchelonGraph's Tier 1 Cloud Scanner automatically checks for this condition across all connected cloud accounts. Violations are flagged as critical-severity findings with remediation guidance.

🔧 Remediation

Audit ClusterRoleBindings: kubectl get clusterrolebindings -o yaml | grep cluster-admin. Replace with namespace-scoped roles for application workloads.

💀 Real-World Attack Scenario

A CI/CD pipeline's service account was granted cluster-admin 'temporarily' during a debugging session. The grant persisted for 8 months. When the pipeline was compromised via malicious notebook upload, attacker had cluster-admin from the first minute. Total impact: $4.2M.

💰 Cost of Non-Compliance

Over-privileged service accounts: 4.6× higher breach impact (IBM 2024).

📋 Audit Questions

  • 1.Who has cluster-admin?
  • 2.Justification per identity?
  • 3.Service accounts with cluster-admin?
  • 4.Audit cadence?

🎯 MITRE ATT&CK Mapping

T1098 — Account ManipulationT1078 — Valid Accounts

⚡ Common Pitfalls

  • Temporary cluster-admin that becomes permanent
  • Auto-generated default SA tokens auto-mounted
  • Wildcard verbs in RoleBindings

📈 Business Value

Restricting cluster-admin contains the worst-case K8s breach scenario.

⏱️ Effort Estimate

Manual

Quarterly review

With EchelonGraph

EchelonGraph audits cluster-admin grants continuously

🔗 Cross-Framework References

NIST-AC-6

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