Cloud Security

Docker Security Best Practices: Top 10 Practices

Organizations must prepare and plan well-crafted Docker files to avoid common security issues such as privileged containers and exposed ports and be left vulnerable or open to emerging threats. Eliminating known risks and implementing Docker Security Best Practices will prepare organizations well for emerging threats. This blog dives into the fundamentals of Docker security and […]

Mansi B.

Written by Mansi B.

August 29, 2023 | 7 min read

Organizations must prepare and plan well-crafted Docker files to avoid common security issues such as privileged containers and exposed ports and be left vulnerable or open to emerging threats. Eliminating known risks and implementing Docker Security Best Practices will prepare organizations well for emerging threats.

This blog dives into the fundamentals of Docker security and covers popular security measures companies deploy to maximize protection. It will cover areas such as enforcing shift-left security by implementing least privilege access, using container image monitoring tools, preventing granting root permissions, and many more.

Table of Contents

  1. What is Docker?
  2. What is Container Security?
  3. Why is Docker Security Important?
  4. Things to Consider Before Working On Improving Docker Security
  5. Top 10 Docker Security Best Practices
  6. How PingSafe Can Help in Docker Security?
  7. Conclusion

What is Docker?

Docker is an open-source platform that allows developers to design, package, deploy, run, manage, and repurpose containers in cloud environments. It has many moving components, and securing Docker containers is complex. Docker deployments adopt a holistic approach to security and ensure everything is secured and works as intended – from container runtime hosts, firewalls, networks, and applications, thus providing optimum protection.

To date, more than 3.5 million applications have been containerized by Docker. It is viral among developers because it is lightweight, portable, and automates software delivery. It also makes security teams more agile and enables them to isolate code into single containers for more straightforward modifications and updates.

What is Container Security?

Container Security is a core component of critical security assessments. It encompasses using various tools and processes to analyze security threats and remediate them before they escalate and impact organizations.

Container security protects containerized applications from potential threats, manages risks, and secures all aspects of the supply chain and Ci/CD pipeline. It safeguards cloud infrastructure, secures container runtime, and runs container lifecycle management applications seamlessly.

Container network security is integral to container security and adds context awareness to applications during container orchestration. Docker security best practices feature a set of guidelines and tips that users can incorporate. It maximizes container security and secures container orchestration modules in the process.

Why is Docker Security Important?

A significant increase in the adoption of containerized applications has prompted malicious actors to target organizations. Docker containers have inherent security features, but with increased application isolation comes the added risk of expanding attack surfaces. Docker container security is important because containers can have multiple vulnerabilities. A single breach or tampering of container images can serve as the entry point to organizations for hackers. There are instances of malicious code found within containers, and container attacks are known to escalate quickly.

Traditional security monitoring methods do not offer sufficient protection against lateral movement attacks. Securing Docker containers can reduce an organization’s security risks, build reputation, and improve user trust.

Things to Consider Before Working On Improving Docker Security

Here are a few steps users can take to improve the base security of Docker containers. These are essential and a part of Docker security best practices.

  1. Choose the right Docker container base image
  2. Use multi-stage builds
  3. Rebuild Images

1. Choose the right Docker container base image

Keeping Docker container images small and ensuring they come from a trusted source can enhance default security. Many unofficial repositories users download Docker container images from these days. Users can automatically reduce the likelihood of confronting malicious code in containers by handpicking images from verified publishers and official repositories.

2. Use multi-stage builds

Multi-stage builds create optimized Docker files that are convenient to read and maintain. It also helps users copy artifacts from other images and eliminates features they don’t need, minimizing attack surfaces.

3. Rebuild Images

Docker files contain imported libraries and allow custom software installations. Rebuilding Docker container images helps prevent expected vulnerabilities and addresses them at their roots.

Top 10 Docker Security Best Practices

Here are the top 10 Docker security best practices for organizations:

  1. Use the Principle of Least Privilege
  2. Keep Docker Containers and Hosts Up to Date
  3. Implement Container Network Segregation
  4. Enable Read-Only to Volumes and File Systems
  5. Limit Docker Resource Utilization
  6. Leverage Container Image Security
  7. Enforce On-Failure Container Restart Policy
  8. Monitor Network Traffic and Access
  9. Enhance Docker Container Isolation
  10. Restrict System Calls within Docker Containers

1. Use the Principle of Least Privilege

When building and deploying Docker applications, sticking to the principle of least privilege access restriction, resource, and account access is crucial. It is one of the top ways to secure Docker containers from unauthorized usage and is among the best Docker security best practices.

Users should configure Docker settings not to run containers as root, and this will help eliminate any entry points, thus preventing privilege escalations.

2. Keep Docker Containers and Hosts Up to Date

It is easy to prevent unknown vulnerabilities when Docker containers are kept up to date. It is essential to patch the Docker Engine and its underlying host operating system since both the container and host share the kernel. A kernel exploit can break a container and allow attackers to take advantage of non-privileged containers quickly. It can also lead to them gaining root access and cause further damage.

One of the many Docker security best practices is to run Docker containers in rootless mode and Docker daemons within user namespaces.

3. Implement Container Network Segregation

All Docker containers rely on a network layer to communicate through network interfaces on the host, and users can create as many networks as they want. The default bridge network is set to all hosts, and it’s essential to change this setting so containers don’t connect to the default host.

It is strongly recommended to use custom bridge networks to communicate between containers and enable automatic DNS resolution.

Avoid linking sensitive containers to public-facing networks and use the Docker network drivers to create overlay networks, bridges, and more. Users can also benefit from the Docker network plugin for more control and optimized network utilization. Container network segmentation is one of the top Docker security best practices.

4. Enable Read-Only to Volumes and File Systems

One top Docker security best practice is setting volumes and file systems to read-only. Users can use the Docker CLI tool or the Docker-compose wrapper to fill in flags automatically and set containers to ready-only by default.

5. Limit Docker Resource Utilization

Docker allows users to limit CPU and memory utilization for each container. Setting and not exceeding resource quotas is a good idea, as it helps run system resources efficiently. Setting resource quotas will also limit the scope of attack surfaces and block attacks that aim to disrupt business operations by consuming too many resources. Limiting resource utilization is a core component of Docker security best practices.

6. Leverage Container Image Security

An excellent way to implement Docker container image security is to conduct static analysis on images and evaluate them via user-defined checks. Docker security best practices include container image scanning for detecting various vulnerabilities. It scans for malicious code in packages for both non-OS and OS components and enforces policy rules for optimum container configuration. Some security tools offer compliance checks for container images created in CI/CD pipelines and allow users to configure policies after analyzing exposed ports, passwords, secrets, files, packages, and image metadata. Another good practice is to avoid sharing the host network’s namespace and not run SSH in containers.

7. Enforce the On-Failure Container Restart Policy

Users can set the on-failure container restart policy and specify how to restart containers on exit. Containers constantly exiting and attempting to restart may introduce denial of service threats. Ignoring containers’ exit status could be better as it adds hidden vulnerabilities and may lead to non-investigations.

Users can configure the on-failure container restart policy when setting Docker security best practices within the organization. It will limit the number of exit attempts and prevent containers from undergoing too many retries. It will also make it easier to perform root cause analysis and remediate issues from the core. 

8. Monitor Network Traffic and Access

Containers send egress traffic to networks; controlling and regulating it is critical. Many tools can accomplish this. A key factor is to enable the automatic detection of traffic flow between containers and monitor it. Security issues like network anomalies are detected by using port scanning techniques. 

9. Enhance Docker Container Isolation

Another of our top Docker security best practices is enforcing container isolation. It is one of the best ways to protect Docker containers and separate global resources. Users can leverage AppArmor Linux kernel enhancements or Red Hat Linux distributions to isolate Docker containers. These feature various access controls and policies for limiting the usage of Docker containers and applications.

10. Restrict System Calls within Docker Containers

Not all Docker containers need to run system calls within them. Users can monitor containers and explicitly allow selected calls according to their requirements. It is recommended to implement this among other Docker security best practices.

How PingSafe Can Help in Docker Security?

PingSafe enhances container security by implementing the top Docker security best practices. It brings a Cloud-Native Application Protection Platform (CNAPP) and implements state-of-the-art Cloud Security Posture Management (CSPM). PingSafe can detect Docker container misconfigurations before deployment, immediately remediate them, and adopt a 360-degree approach to security. It secures cloud VMs and Docker containers and can protect serverless functions.

PingSafe can detect vulnerabilities in container images, generate graph-based visualizations for Docker and Kubernetes clusters, and generate SBOM code for each image. It offers CI/CD integration support, performs IaC deployments, and can monitor IaC scripts for fixing misconfiguration issues. It even supports using CloudFormation and TerraForm templates, performs zero-day vulnerability assessments, and comes with a threat watch dashboard. The platform can deliver agentless VM snapshot scanning and simulate attacks from an attacker’s perspective during penetration tests. This gives insights into multiple threat vectors and enables organizations to prepare for future threats.

PingSafe provides real-time detection of cloud credentials and can validate Docker secrets. It can weed out false positives, verify the validity of detected secrets, and monitor domain names. PingSafe prevents cloud credential leakage and enables native integrations with GitLab, GitHub, and BitBucket.

All Docker container images are secured, following the latest compliance policies and recommendations. Some popular industry compliance standards PingSafe supports are PCI/DSS, HIPAA, SOC2, ISO, and CIS. It can also export compliance reports and has widgets that track, open, and resolve issues with the latest threat trends.

Regarding Docker user management, PingSafe enables organizations to restrict access to sensitive information and limits resource usage. It applies Role-Based Access Control, single sign-off, and event analyzer capabilities and offers multi-tenancy support.

Conclusion

Docker containerized applications may introduce additional vulnerability as the cloud security landscape evolves. Whenever developers release new security features, attackers develop new hijacking techniques and increase sophistication. These are the top Docker Security Best Practices because they focus on the basics. Host security management, container runtime monitoring, and container image scanning make up the building blocks of Docker container security.

Users can achieve a strong Docker security posture by implementing these tips and preparing for the future.