12 Best Practices for Securing Kubernetes (K8s) Environments

Kubernetes (K8s) clusters often consist of dozens to thousands of nodes, and their configuration is critical for security; many security features are not enabled by default, making hardening essential.

1. Upgrade to the latest stable K8s version to obtain security patches and new security features, reducing the attack surface.

2. Enforce PodSecurityPolicy (PSP) by enabling the PSP admission controller and defining policies that prevent privileged containers, restrict host namespace sharing, limit volume types, enforce read‑only root filesystems, and apply the principle of least privilege.

3. Use namespaces for resource isolation , creating logical partitions, enforcing resource separation, and avoiding the use of the kube- prefix for custom namespaces.

4. Apply NetworkPolicy as a firewall for Pods, using plugins such as Calico, Cilium, Kube‑router, Romana, or Weave Net, and adopting a default‑deny‑all stance with selective allow rules based on labels.

5. Deploy ImagePolicyWebhook to block unverified images, including those not scanned, not whitelisted, or from insecure registries.

6. Harden the Kubernetes API server by reviewing its process arguments (e.g., ps -ef | grep kube-apiserver ) and ensuring secure TLS settings, proper authentication, and restricted access.

7. Secure the kube‑scheduler by disabling profiling, binding to 127.0.0.1 , and limiting exposure.

8. Secure the kube‑controller‑manager with appropriate flags such as --terminated-pod-gc-threshold , disabling profiling, enabling service‑account credentials, and restricting address binding.

9. Harden etcd by enabling TLS with --cert-file and --key-file , enforcing client‑certificate authentication, and separating etcd certificates from those used by the API server.

10. Secure kubelet by setting --anonymous-auth=false , avoiding AlwaysAllow for authorization, configuring --client-ca-file , disabling the read‑only port, protecting kernel defaults, and ensuring TLS certificates are properly set.

11. Protect master‑node configuration files by verifying permissions and ownership of API server, controller‑manager, scheduler, and etcd manifest files, as well as PKI directories.

12. Protect worker‑node configuration files by checking permissions and ownership of kubelet service files, kubelet.conf, and related certificates.

By following these twelve practices, administrators can significantly reduce common misconfiguration‑related security risks in Kubernetes deployments.