mediumMultiple ChoiceObjective-mapped
CKS Practice Question: Auditing RBAC and find a ClusterRoleBinding named…
You are auditing RBAC and find a ClusterRoleBinding named 'admin-binding' that binds the 'cluster-admin' ClusterRole to a service account in the 'default' namespace. What is the security concern?
⚠ Common exam trap
The trap here is that candidates may focus on the binding type (ClusterRoleBinding vs RoleBinding) or namespace usage, rather than recognizing that the core issue is the excessive privileges of the 'cluster-admin' role itself, regardless of how it is bound.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
It grants too broad permissions to the service account
The 'cluster-admin' ClusterRole grants super-user permissions across the entire cluster, including access to all namespaces and all resources. Binding this role to a service account via a ClusterRoleBinding gives that service account unrestricted cluster-wide privileges, which violates the principle of least privilege. This is a significant security concern because if the service account is compromised, an attacker gains full control over the cluster.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The binding should be a RoleBinding instead of ClusterRoleBinding
Why it's wrong here
Even with a RoleBinding in a namespace, cluster-admin still grants cluster-wide permissions if bound to a ClusterRole.
- ✓
It grants too broad permissions to the service account
Why this is correct
Correct. cluster-admin gives superuser access, which should be avoided for service accounts.
- ✗
The service account name must be changed
Why it's wrong here
The name is not a security concern.
- ✗
The binding is fine as long as the service account is used in the default namespace
Why it's wrong here
No, the wide permissions are still a risk.
Quick reference
Access Control Model Comparison
| Model | Acronym | Who Controls Access? | Best For |
|---|---|---|---|
| Discretionary Access Control | DAC | Resource owner | Small teams, file shares |
| Mandatory Access Control | MAC | System / security labels | Classified govt / military |
| Role-Based Access Control | RBAC | Administrator (via roles) | Enterprise environments |
| Attribute-Based Access Control | ABAC | Policy engine (user + resource attributes) | Fine-grained, dynamic policies |
| Rule-Based Access Control | RuBAC | System rules / ACLs | Firewall rules, network ACLs |
Go deeper
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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