---
title: chown flag exists
description: Datadog, the leading service for cloud-scale monitoring.
breadcrumbs: >-
  Docs > Datadog Security > Code Security > Infrastructure as Code (IaC)
  Security > IaC Security Rules > chown flag exists
---

# chown flag exists

{% callout %}
# Important note for users on the following Datadog sites: app.ddog-gov.com

{% alert level="danger" %}
This product is not supported for your selected [Datadog site](https://docs.datadoghq.com/getting_started/site.md). ().
{% /alert %}

{% /callout %}

## Metadata{% #metadata %}

**Id:** `aa93e17f-b6db-4162-9334-c70334e7ac28`

**Cloud Provider:** Dockerfile

**Platform:** Dockerfile

**Severity:** Low

**Category:** Best Practices

#### Learn More{% #learn-more %}

- [Provider Reference](https://docs.docker.com/develop/develop-images/dockerfile_best-practices/)

### Description{% #description %}

Setting file ownership to a non-root user in a Dockerfile using the `--chown` flag can leave executables or sensitive files writable by the runtime user. This can enable tampering, persistence of malicious artifacts, or privilege escalation.

This rule flags Dockerfile instructions (for example, `COPY` or `ADD`) that include the `--chown` flag; Dockerfile commands must not use `--chown`. To remediate, remove `--chown` from `COPY`/`ADD` and ensure files remain root-owned with restrictive permissions (for example, use `RUN chmod`), or perform any necessary, controlled ownership changes at container startup rather than using `--chown` in image build.

Secure example:

```dockerfile
# Copy files without --chown so they remain owned by root in the image
COPY app/mybinary /usr/local/bin/mybinary
RUN chmod 0555 /usr/local/bin/mybinary
```

## Compliant Code Examples{% #compliant-code-examples %}

```dockerfile
FROM python:3.7
RUN pip install Flask==0.11.1
RUN useradd -ms /bin/bash patrick
COPY app /app
WORKDIR /app
USER patrick
CMD ["python", "app.py"]
```

## Non-Compliant Code Examples{% #non-compliant-code-examples %}

```dockerfile
FROM python:3.7
RUN pip install Flask==0.11.1
RUN useradd -ms /bin/bash patrick
COPY --chown=patrick:patrick app /app
WORKDIR /app
USER patrick
CMD ["python", "app.py"]
```