How to Implement a Security Scanner for Docker Images
Are you using Docker to deploy your applications? If so, you’re not alone. The use of Docker has skyrocketed in popularity in recent years. While it offers numerous benefits, it also introduces new security risks that need to be addressed.
From losing customer trust to spending heavily on incident response management tools and processes, the consequences of a security incident can be severe. That’s why it’s crucial to take steps to prevent them from occurring in the first place.
Enter Docker image security scanners. These tools can help you identify and fix vulnerabilities in your Docker images before they can be exploited by malicious actors. But where and how do you start?
In this article, we’ll provide tips for implementing a Docker image security scanner and discuss the practices that other organizations use to reduce security incidents. The goal is to prevent a security breach from derailing your product’s success.
Revisiting Docker and Docker Images
If you’re new to Docker, here’s a brief overview:
Docker is a platform for deploying applications in containers.
A Docker image is a lightweight, stand-alone, executable package that includes everything needed to run a piece of software, including the code, a runtime, libraries, environment variables and config files.
Docker images serve as the foundation for Docker containers and are used to build, ship and run containers.
In short, Docker helps you deploy applications in containers, and Docker images are the packages that make up those containers.
Introduction to Security Scanners
Let’s delve into the world of Docker image scanners by using an analogy to help illustrate their purpose and function.
Imagine you are building a house. You carefully select the materials, hire a reliable contractor and follow all the necessary building codes and regulations. However, even with all these precautions, your house is not completely secure until you perform a thorough inspection to identify any potential weaknesses or vulnerabilities.
This is where security scanners come in. Just like a home inspector checks for structural issues and potential hazards, security scanners scan your systems, networks and applications for vulnerabilities and security weaknesses. In the context of Docker, security scanners can be used to scan Docker images for vulnerabilities and other security issues.
Imagine each layer of a Docker image as a brick in a wall. Even if you use high-quality bricks and build the wall according to the right specifications, it is still possible for a malicious actor to find a way to break through. This is where security scanners come in. They scan each brick (layer) of the wall (image) to identify any vulnerabilities that could be exploited.
By implementing a Docker image security scanner, you can ensure the security of your Docker deployments and reduce the risk of security incidents. Just like a home inspector gives you peace of mind that your house is safe and secure, a Docker image security scanner gives you confidence that your Docker deployments are secure.
Inspecting the Vulnerabilities
Acting on the reports generated by Docker image scanners is an important part of maintaining the security of your Docker deployments. When a report identifies vulnerabilities or other security issues, it is important to take steps to address these issues as soon as possible.
Once you have decided to take action on the report, consider the following points.
Fixing the Vulnerability
Do you recall the building analogy we previously discussed? Let’s revisit that.
Imagine a building inspection report that identifies structural issues or safety hazards. Just like you would prioritize and fix these issues to ensure the safety and stability of the building, you should prioritize and fix the vulnerabilities and other security issues identified by a Docker image scanner report.
The most severe issues should be addressed first, as they pose the greatest risk to your organization. You may also want to prioritize issues based on their likelihood of being exploited, as well as the impact they could have on your organization if they are exploited.
Once you have prioritized the issues, you can begin working to fix them. This may involve updating the Docker image to a version that addresses the vulnerability or implementing workarounds or mitigations to reduce the risk of exploitation.
Testing the Fixes
Just like you would test the repairs to a building to ensure they are effective, it is important to thoroughly test any fixes to ensure that they are effective and do not introduce new vulnerabilities or issues.
In addition to fixing the issues identified in the report, it is also important to establish a process for regularly inspecting the building (or in this case, scanning Docker images) and addressing any new issues that are identified.
This can help ensure that your Docker deployments remain secure over time, just like regularly inspecting a building helps ensure its safety and stability.
Overall, the best approach to fixing the red flags generated by a Docker image scanner report is to prioritize and address the issues in a timely and effective manner and to establish a process for regularly scanning and addressing new issues.
Improving Docker image security is a crucial task for organizations that rely on containerized applications. Here are some best practices for achieving this:
Use Official Images
Always use official images from trusted sources like Docker Hub or your organization’s internal registry. These images have undergone thorough security checks and are less likely to have vulnerabilities.
Use Minimal Base Images
Use base images that have the minimum set of libraries and dependencies required to run your application. This reduces the attack surface area and makes it easier to maintain and update the image.
Keep Images up to Date
Regularly update the base image and all libraries and dependencies in the image. This ensures that you are using the most secure version of these components.
Scan Images for Vulnerabilities
Use tools like Anchore, Snyk and Twistlock to scan images for known vulnerabilities. These tools use databases like the National Vulnerability Database (NVD) to identify vulnerabilities and provide recommendations for fixes.
Use Multistage Builds
Use multistage builds to separate the build and runtime environments in the image. This helps to keep the runtime image minimal and reduces the risk of vulnerabilities being introduced during the build process.
Use Secrets Management Tools
Use secrets management tools like HashiCorp Vault or AWS Secrets Manager to store sensitive information like passwords and keys. This ensures that such information is not stored in the image, which could be accessed by attackers.
It is important to follow these practices to ensure that your docker images are secure. Failing to do so could result in vulnerabilities being introduced into the image, leading to security breaches and data loss. Therefore, it is essential to prioritize image security and follow best practices to ensure the integrity of your containerized applications.
Overview of Various Docker Security Scanning Tools
There are several Docker image security scanner tools available in the market. Here is a brief overview of some of the popular ones:
This open source tool analyzes Docker images and identifies vulnerabilities, policy violations and other security risks. It provides detailed reports and recommendations for remediation.
This tool scans images for vulnerabilities and provides recommendations for remediation. It also offers features like dependency analysis and remediation guidance.
This tool scans images for vulnerabilities, malware and compliance violations. It also provides runtime protection for containers and Kubernetes environments.
These are just a few examples of the numerous docker image security scanner tools available in the market. It is important to choose a tool that meets the specific security needs of your organization.
Implementing and Configuring Anchore
The following steps are involved when implementing and configuring Anchore:
- To install Anchore, you need to have Docker and Git installed on your system.
- Use the following command to install anchore:
docker run -d --name anchore-engine -p 8228:8228 -v /var/lib/anchore-engine:/config anchore/engine:v0.7.2
- Once the installation is complete, you need to configure Anchore to scan images. You can do this by creating a configuration file at
- You can specify the configuration options like the Docker registry URL, credentials and the name of the policy to be used for scanning.
- To scan an image, you can use the Anchore CLI tool. First, you need to add the image to the Anchore engine using the following command:
anchore-cli image add <image-name>
- Next, you can use the following command to scan the image. This will scan the image and provide a report with details of any vulnerabilities or policy violations found.
anchore-cli image evaluate <image-name>
- If the scan reveals any vulnerabilities, you can use the recommendations provided by Anchore to fix them. You can also create custom policies to specify the security requirements for your images.
- It is important to regularly scan images using Anchore to ensure that they are secure and free from vulnerabilities. By following these steps, you can effectively implement and configure Anchore to secure your Docker images.
Implementing a Docker image security scanner can greatly reduce security incidents by ensuring that only secure and trusted images are deployed in your environment. By automating this process, you can save time and resources while also increasing the overall security of your systems.
It is important to regularly scan and update your images to stay up to date with the latest security patches and vulnerabilities.