# Cis Docker 3.7

> Ensure that registry certificate file ownership is set to root:root

- Skill: `cyberstrikeus/cis-docker-3-7` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/cis-docker-3-7`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/cis-docker-3-7/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-docker-3-7

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# Ensure that registry certificate file ownership is set to root:root (Manual)

## Profile Applicability

- Level 1 - Docker - Linux

## Description

You should verify that all the registry certificate files (usually found under `/etc/docker/certs.d/<registry-name>` directory) are individually owned and group owned by `root`.

## Rationale

The `/etc/docker/certs.d/<registry-name>` directory contains Docker registry certificates. These certificate files must be individually owned and group owned by `root` to ensure that less privileged users are unable to modify the contents of the directory.

## Impact

None.

## Audit Procedure

You should execute the command below to verify that the registry certificate files are individually owned and group owned by `root`:

```bash
stat -c %U:%G /etc/docker/certs.d/* | grep -v root:root
```

The above command should not return any value.

## Remediation

The following command could be executed:

```bash
chown root:root /etc/docker/certs.d/<registry-name>/*
```

This would set the individual ownership and group ownership for the registry certificate files to `root`.

## Default Value

By default, the individual ownership and group ownership for registry certificate files is correctly set to `root`.

## References

1. https://docs.docker.com/registry/insecure/

## CIS Controls

| Controls Version | Control                                                                                                                                                                                                                                                                                                                      | IG 1 | IG 2 | IG 3 |
| ---------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---- | ---- | ---- |
| v8               | 5.4 Restrict Administrator Privileges to Dedicated Administrator Accounts - Restrict administrator privileges to dedicated administrator accounts on enterprise assets. Conduct general computing activities, such as internet browsing, email, and productivity suite use, from the user's primary, non-privileged account. | ●    | ●    | ●    |
| v7               | 4 Controlled Use of Administrative Privileges - Controlled Use of Administrative Privileges                                                                                                                                                                                                                                  |      |      |      |