Cis K8s V1110 1.3.5

---
name: cis-k8s-v1110-1.3.5
description: "Ensure that the --root-ca-file argument is set as appropriate (Automated)"
category: cis-k8s
version: "1.11.0"
author: cyberstrike-official
tags: [cis, kubernetes, control-plane, controller-manager, root-ca, tls]
cis_id: "1.3.5"
cis_benchmark: "CIS Kubernetes Benchmark v1.11.0"
tech_stack: [kubernetes]
cwe_ids: []
chains_with: []
prerequisites: []
severity_boost: {}
---

# 1.3.5 Ensure that the --root-ca-file argument is set as appropriate (Automated)

## Profile Applicability

- Level 1 - Master Node

## Description

Allow pods to verify the API server's serving certificate before establishing connections.

## Rationale

Processes running within pods that need to contact the API server must verify the API server's serving certificate. Failing to do so could be a subject to man-in-the-middle attacks.

Providing the root certificate for the API server's serving certificate to the controller manager with the `--root-ca-file` argument allows the controller manager to inject the trusted bundle into pods so that they can verify TLS connections to the API server.

## Impact

You need to setup and maintain root certificate authority file.

## Audit

Run the following command on the Control Plane node:

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

Verify that the `--root-ca-file` argument exists and is set to a certificate bundle file containing the root certificate for the API server's serving certificate.

## Remediation

Edit the Controller Manager pod specification file `/etc/kubernetes/manifests/kube-controller-manager.yaml` on the Control Plane node and set the `--root-ca-file` parameter to the certificate bundle file.

```
--root-ca-file=<path/to/file>
```

## Default Value

By default, `--root-ca-file` is not set.

## References

1. https://kubernetes.io/docs/admin/kube-controller-manager/
2. https://github.com/kubernetes/kubernetes/issues/11000

## 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    |