Docker Image Vulnerabilities and Scanner Guide: A Quick Overview

Vulnerabilities in Docker images can expose your system to potential cyber threats. Tools like Docker Scout, Trivy,.. offer a fast and comprehensive way to scan for these vulnerabilities, ensuring a secure containerized environment.

What is a Vulnerability?

A vulnerability is a weakness or flaw in software that can be exploited by attackers to compromise a system’s security. In the context of Docker, vulnerabilities can exist within container images, making them potential entry points for cyber threats.

Docker Image Vulnerabilities

Docker images serve as the building blocks for containers. These images can contain outdated or flawed components that may pose security risks. Identifying and mitigating these vulnerabilities is crucial for a secure containerized environment.

Image Vulnerability Database: https://dso.docker.com/explore

Here are the top 5 tools to scan Docker images:

1. Docker scout
2. Trivy
3. Clair
4. Anchore Engine
5. Dagda
6. Synk

Scan Docker Images

Using Docker Scout is simple. With a single command, you can scan a Docker image to reveal potential vulnerabilities. This step should be integrated into your CI/CD pipeline for automated security checks.

You can use different tool also based on your requirement.

Docker Scout

Docker Scout analyzes your images to help you understand their dependencies and potential vulnerabilities

docs.docker.com

## My Sample Docker File

FROM node:20-slim
WORKDIR /app
MAINTAINER gudditi
COPY . .
RUN npm install
EXPOSE 3000
ENTRYPOINT [ "node", "app.js"]

Source : https://github.com/GudditiOrg/3-tier-app

Let’s build and scan the docker image:

I am using Git Actions for this. We will build the Docker image in GitHub, scan it, and obtain detailed information about it.

name: Docker Image CI

on:
  push:
    branches: [ "main" ]
  pull_request:
    branches: [ "main" ]jobs:  build:    runs-on: ubuntu-latest    steps:
    - uses: actions/checkout@v3
    - name: Build the Docker image
      run: docker build . --file Dockerfile --tag gudditi/node-app:latest
      
    - name: Docker Scout
      uses: docker/scout-action@v0.18.1
      with:
        command: quickview,cves,sbom,recommendations
        image: gudditi/node-app:latest
        ignore-unchanged: true
        only-severities: high, medium, low, unspecified
        write-comment: false

• This Git Actions configuration checks out the latest code from the repository.
• It then sets up the Docker environment and includes Docker Scout.
• Following this, it proceeds to build the Docker image.
• The resulting image is then scanned by Docker Scout.
• Docker Scout provides detailed information about the scanned image.

The reports look like this :

Based on the vulnerabilities report recommendations, you are responsible for updating the packages with the highest priority. We can also utilize other tools based on specific requirements, ensuring Docker images are vulnerability-friendly.