Docker CIS Benchmark: Best Practices in Brief

What is Docker CIS Benchmark?

The Center for Internet Security (CIS) researches best practices for cybersecurity in containerized environments. CIS publishes the Docker CIS Benchmark, a comprehensive list of best practices that can help you secure Docker containers in production.

The Docker CIS Benchmark focuses on ensuring Docker containers runtimes are configured as securely as possible. You can download the full Docker CIS Benchmark for free from the Center for Internet Security.

This post summarizes Docker security best practices in the CIS benchmark, and provides details on three tools that can automatically test for Docker security best practices.

In this article, you will learn:

• Docker CIS Benchmark Best Practices
• Host Configuration
• Docker Daemon Configuration
• Docker Daemon Configuration Files
• Container Images and Build File Configuration
• Container Runtime Configuration
• Docker Security Operations
• Docker Swarm Configuration
• Docker Enterprise Configuration
• Docker Security Benchmark Tools
• Docker Bench for Security
• OpenSCAP Workbench
• Anchore

Docker CIS Benchmark Best Practices

The Docker CIS Benchmark is an extensive document with detailed recommendations about securing Docker in production. Below we provide a summary of the recommendations to help you get a head start on the CIS best practices.

Related content: read our guide to Docker architecture ›

Host Configuration

The CIS benchmark has several recommendations for securing the host on which the Docker engine runs.

Docker Daemon Configuration

Here are the CIS recommendations for securing the behavior of the Docker daemon, the background process that manages all containers on the Docker host.

Related content: read our guide to seccomp ›

Docker Daemon Configuration Files

The Docker Daemon configuration files are highly sensitive and can allow an attacker to control all containers on the host. Here are the CIS recommendations for securing these files.

This section covers Docker related files and directory permissions and ownership. Keeping the files and directories, that may contain sensitive parameters, secure is important for correct and secure functioning of Docker daemon.

Container Images and Build File Configuration

Container base images and the build files used to create them dictate what is inside a container and how it operates. Ensure your base images and build files are safe and trusted. Here are CIS recommendations for images.

Container Runtime Configuration

The way a container is configured to start has a major impact on security. Certain runtime parameters can lead to compromise of the host and the containers running on it. Here are CIS recommendations for container startup and runtime configuration.

Docker Security Operations

Here are two key CIS recommendations with regard to securely operating Docker in production:

• Avoid image sprawl—it is a best practice not to use too many container images on the same host. All images on the host must be tagged. Untagged images or images with old tags may contain vulnerabilities.
• Avoid container sprawl—do not run too many containers on the same host. Having more containers on the host than optimal can expose the Docker host to mishandling, misconfiguration, and fragmentation. 

Docker Swarm Configuration

Docker Swarm is Docker’s container orchestrator, which can manage clusters of containers and their lifecycle. Here are CIS recommendations for running Docker Swarm securely.

Docker Enterprise Configuration

Docker Enterprise Edition (EE) by Mirantis is Docker’s enterprise-grade container platform for CentOS, RHEL, SUSE Linux Enterprise, Oracle Linux, and Windows Server. Here are CIS recommendations for securely running Docker EE.

Related content: read our guide to container registry scanning ›

Docker Security Benchmark Tools

The Docker CIS Benchmark provides hundreds of detailed recommendations for Docker configuration. It is impractical to manually check all these best practices, especially for large container deployments. Below are three free tools that can help you automatically test that your containers meet the CIS best practices, and provide suggestions for remediation.

Docker Bench for Security

Docker Bench for Security is an open source script that audits containers according to the CIS benchmark’s best practices. It performs tests based on CIS benchmark recommendations, and logs its findings. 

For each CIS benchmark recommendation, the tool provides Info (issues found), Warning (container does not meet the recommendation), or Pass (container is compliant). You can run the tool from the Docker host, directly on the host operating system, or clone it with Docker Compose.

OpenSCAP Workbench

OpenSCAP includes multiple open security benchmark guidelines, configuration criteria, and open source tools that can help test for security issues, including the CIS benchmark. It is focused on the NIST-certified Secure Content Automation Protocol (SCAP), which includes many automated security policies. 

OpenSCAP goes wider than the CIS recommendations, including many other recommendations, some of which are not specific to a containerized environment. It can be useful for identifying additional security concerns not covered by the CIS guidelines.

Anchore

Anchore Engine is a tool for analyzing container images. It can identify CVE-based vulnerabilities in containers, and also lets users define custom policies and use them to evaluate Docker images. Policies can be based on whitelist, blacklist, credentials, file contents, and configurations.

While anchor does not officially support CIS benchmark guidelines, you can define custom policies to cover all benchmark recommendations. For each policy, Anchore returns a pass or fail result.

Anchor can run as a Docker container image, within Kubernetes, or as a standalone binary. It integrates with popular CI/CD tools like Jenkins and GitLab.