# Cis K8S V1110 1.3.5

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

- Skill: `cyberstrikeus/cis-k8s-v1110-1-3-5` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/cis-k8s-v1110-1-3-5`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/cis-k8s-v1110-1-3-5/raw
- Safety review: PASS (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: DevOps & Infra
- Author: cyberstrikeus (https://skillmd.com/u/cyberstrikeus)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/cyberstrikeus/cis-k8s-v1110-1-3-5

---


# 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    |