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Understanding CIS Benchmarks for Kubernetes

Required knowledge for the CKS certification.

What are CIS Benchmarks?​

CIS (Center for Internet Security) Benchmarks are a set of best practices and guidelines to help secure systems, including Kubernetes clusters. They provide actionable security recommendations to harden the Kubernetes environment, reducing potential attack vectors and improving overall security.

Why Are CIS Benchmarks Important?​

  1. Standardization: Ensures your Kubernetes cluster meets globally recognized security standards.
  2. Compliance: Helps with compliance requirements, such as HIPAA, PCI-DSS, and GDPR.
  3. Security Posture: Enhances the security posture of the Kubernetes control plane, nodes, and workloads.

Key Areas Covered by CIS Kubernetes Benchmarks​

The CIS Benchmarks for Kubernetes cover several critical areas:

1. Control Plane Components​

  • Kube-apiserver: Authentication, authorization, and audit log configuration.
  • Kube-controller-manager: Securing certificates and minimizing privileges.
  • Kube-scheduler: Ensuring secure communication.

2. Worker Nodes Security​

  • Securing the kubelet process.
  • Using read-only ports and TLS authentication.
  • Configuring Pod Security Policies (PSP) and Pod Security Standards (PSS).

3. Networking​

  • Enforcing Network Policies to control ingress and egress traffic.
  • Avoiding insecure HostNetwork and HostPort usage.

4. Policies and Configuration​

  • Using RBAC (Role-Based Access Control) for granular permissions.
  • Implementing Security Contexts and Pod Security Standards.
  • Avoiding privileged containers and enforcing resource limits.

Example: Enforcing CIS Benchmarks with kube-bench​

You can use kube-bench, an open-source tool, to automate CIS Benchmark checks:

# Run kube-bench on a Kubernetes node
curl -L https://github.com/aquasecurity/kube-bench/releases/download/v0.6.9/kube-bench_0.6.9_linux_amd64.tar.gz | tar xz
./kube-bench --config-dir cfg --config cfg/config.yaml

Sample Output​

[INFO] 1.1.1 Ensure that the --anonymous-auth argument is set to false (Scored)
[PASS] 1.1.2 Ensure that the --basic-auth-file argument is not set (Scored)
[FAIL] 1.1.3 Ensure that the --token-auth-file parameter is not set (Scored)
  • [PASS] indicates compliance.
  • [FAIL] suggests areas that need remediation.

Best Practices for Meeting CIS Benchmarks​

  1. Automate Security Checks: Integrate kube-bench with your CI/CD pipelines.
  2. Regular Audits: Schedule periodic scans of your cluster to maintain compliance.
  3. Update Policies: Keep RBAC policies, Network Policies, and Pod Security Standards up-to-date.
  4. Harden the Environment: Follow the principle of least privilege and avoid using the default namespace for critical workloads.

Conclusion​

CIS Benchmarks for Kubernetes are a critical tool for securing your cluster against common threats. By implementing these best practices and using tools like kube-bench, you can ensure that your Kubernetes environment is not only compliant but also resilient to attacks.

Last updated on by Itai Ganot