Cis K8s V1110 1.3.6

---
name: cis-k8s-v1110-1.3.6
description: "Ensure that the RotateKubeletServerCertificate argument is set to true (Automated)"
category: cis-k8s
version: "1.11.0"
author: cyberstrike-official
tags: [cis, kubernetes, control-plane, controller-manager, certificate-rotation, kubelet]
cis_id: "1.3.6"
cis_benchmark: "CIS Kubernetes Benchmark v1.11.0"
tech_stack: [kubernetes]
cwe_ids: []
chains_with: []
prerequisites: []
severity_boost: {}
---

# 1.3.6 Ensure that the RotateKubeletServerCertificate argument is set to true (Automated)

## Profile Applicability

- Level 1 - Master Node

## Description

Enable kubelet server certificate rotation on controller-manager.

## Rationale

`RotateKubeletServerCertificate` causes the kubelet to both request a serving certificate after bootstrapping its client credentials and rotate the certificate as its existing credentials expire. This automated periodic rotation ensures that the there are no downtimes due to expired certificates and thus addressing availability in the CIA security triad.

Note: This recommendation only applies if you let kubelets get their certificates from the API server. In case your kubelet certificates come from an outside authority/tool (e.g. Vault) then you need to take care of rotation yourself.

## Impact

None

## Audit

Run the following command on the Control Plane node:

```bash
ps -ef | grep kube-controller-manager
```

Verify that `RotateKubeletServerCertificate` argument exists and is set to `true`.

## Remediation

Edit the Controller Manager pod specification file `/etc/kubernetes/manifests/kube-controller-manager.yaml` on the Control Plane node and set the `--feature-gates` parameter to include `RotateKubeletServerCertificate=true`.

```
--feature-gates=RotateKubeletServerCertificate=true
```

## Default Value

By default, `RotateKubeletServerCertificate` is set to "true" this recommendation verifies that it has not been disabled.

## References

1. https://kubernetes.io/docs/admin/kubelet-tls-bootstrapping/#approval-controller
2. https://github.com/kubernetes/features/issues/267
3. https://github.com/kubernetes/kubernetes/pull/45059
4. https://kubernetes.io/docs/admin/kube-controller-manager/

## CIS Controls

| Controls Version | Control                                           | IG 1 | IG 2 | IG 3 |
| ---------------- | ------------------------------------------------- | ---- | ---- | ---- |
| v8               | 3.10 Encrypt Sensitive Data in Transit            |      | X    | X    |
| v7               | 14.4 Encrypt All Sensitive Information in Transit |      | X    | X    |