7 Container Security Best Practices You Must Know

What Are Container Security Best Practices?

Container security best practices are guidelines and procedures aimed at securing containerized applications and their infrastructure. Containers, which encapsulate an application’s code, configurations, and dependencies into a single object, have become a staple in modern application deployment strategies.

Ensuring the security of containers spans from the image creation phase to the runtime environment, including securing the application code, container orchestration layers, and the underlying infrastructure.

Containers often run critical applications and handle sensitive data. Implementing best practices is therefore essential to safeguard against threats, such as unauthorized access, malicious attacks, or data breaches. This involves a multi-layered security approach that covers every stage of the container lifecycle, from development to deployment and maintenance.

In this article:

The Challenges of Securing Containers

Rapid Deployment and Scalability

The same features that make containers so appealing—rapid deployment and scalability—also introduce significant security challenges. Containers can be deployed and scaled dynamically, often in an automated manner, which can lead to inconsistent security configurations if not carefully managed. Additionally, the ephemeral nature of containers complicates monitoring and logging, making it difficult to track malicious activities or anomalies over time.

Vulnerabilities in Container Images

Container images are foundational to container deployment, but they can also be a source of vulnerability. These images typically contain not just the application and its runtime environment, but also an underlying operating system layer. If an image is outdated or configured insecurely, it introduces potential vulnerabilities that can be exploited by attackers. The challenge is compounded by the fact that images can be easily shared and reused, spreading vulnerabilities across different environments and applications.

Secrets Management

Managing sensitive information such as passwords, tokens, and keys within containerized environments poses unique challenges. Containers are often deployed at a large scale and can be highly transient, making traditional secrets management practices difficult to apply. Embedding secrets in container images or passing them through environment variables, common practices in container deployment, are insecure methods that can expose sensitive information to unauthorized users or applications.

Compliance and Auditing

Ensuring compliance and facilitating auditing in a containerized environment can be particularly challenging. The dynamic and scalable nature of containers, combined with their use in microservices architectures, can create complex networks of interactions and dependencies that are difficult to monitor and control.

This complexity makes it harder to enforce compliance standards and to audit containerized applications and infrastructure for security compliance, data integrity, and access controls. Compliance frameworks and regulations may not always account for the nuances of container technology, requiring organizations to interpret and apply these standards in innovative ways.

Related content: Read our guide to container monitoring (coming soon)

Key Container Security Best Practices

These best practices can help ensure the security of containers and the applications they encapsulate.

1. Secure Container Images

Ensuring images are free from vulnerabilities and securely configured is crucial, as these images serve as the blueprint for container creation. Best practices include using official images from trusted repositories, minimizing the footprint by including only necessary packages, and scanning images for vulnerabilities regularly.

It’s important to maintain image integrity throughout the container lifecycle. This can involve signing images with digital signatures to verify their authenticity and implementing policies that prevent the use of unauthorized images.

2. Enforce the Principle of Least Privilege

The principle of least privilege (PoLP) entails granting only the necessary permissions required for a container or a service to operate, thereby minimizing the attack surface. Implementing PoLP involves careful configuration of access controls and user permissions, both at the container level and for the container orchestration platform.

Enforcing PoLP extends to runtime operations, where containers should be restricted to access only the resources they need to perform their functions. This includes limiting network access, controlling inter-container communication, and restricting access to host resources. Adhering to PoLP helps prevent privilege escalation and limits the damage from compromised containers.

3. Securing Container Runtime

Securing the container runtime involves protecting the containers in operation and the infrastructure they run on. This includes monitoring for suspicious activity, implementing runtime security policies, and ensuring containers operate in a controlled and isolated environment.

Tools and practices such as runtime security tools, anomaly detection, and behavior monitoring can provide real-time security insights. Securing the runtime environment also involves hardening the host system and configuring network policies to limit container access to necessary services and systems.

4. Using Thin, Short-Lived Containers

By designing containers to perform a single function or process and limiting their lifespan, organizations can reduce the attack surface and simplify security management. These containers are easier to monitor, update, and replace, which enhances security responsiveness and agility.

Adopting a microservices architecture, where applications are broken down into smaller, independent services, complements the use of thin, short-lived containers. This approach also enhances scalability and resilience. Regularly cycling containers and keeping them ephemeral discourages persistent threats and facilitates a more dynamic, secure application environment.

5. Segregate Container Networks

Isolating container networks from each other and from the host network prevents lateral movement by attackers and limits the impact of a compromised container. Implementing network policies and using network segmentation tools can control traffic flow between containers, services, and external networks.

Container orchestration platforms offer features to manage network policies, allowing for the definition of granular rules that govern inter-container communication and access controls. By segregating container networks, organizations can enforce a zero-trust network model, ensuring that containers and services verify and authenticate before communicating.

6. Regularly Audit Container Environments

Regular audits are critical for maintaining the security integrity of container environments. These audits help identify vulnerabilities, ensure adherence to security policies, and maintain compliance with regulatory standards.

Automated tools such as container image scanning, static application security testing (SAST) and dynamic application security testing (DAST) should be used to scan for weaknesses in images, application source code, and running containers. It’s also essential to implement comprehensive logging and monitoring for all container activities.

Regularly reviewing access controls and permissions ensures they remain strict and follow the principle of least privilege. Compliance checks should be an integral part of the auditing process, ensuring that container operations align with industry standards and regulations.

7. Update and Patch Regularly

Keeping container images and the container orchestration platform updated is crucial for security. Regular updates and patches eliminate critical security vulnerabilities that could be exploited by attackers.

Organizations should establish a process for regularly checking for updates and patches for all components of their container ecosystem, including the host OS, container runtime, orchestration tools, and the containers themselves. An automated system for deploying updates can help maintain security without disrupting operations.

8. Leverage Container Security Tools

There are numerous tools available designed specifically to enhance container security. These tools can automate many aspects of security, from scanning images for vulnerabilities to monitoring runtime environments for suspicious activities. Integrating these tools into the CI/CD pipeline allows for continuous security assessment throughout the container lifecycle.

Selecting the right tools requires understanding the specific security needs of your container environment and may include features like vulnerability scanning, compliance monitoring, network segmentation, and runtime protection.

Secure Your Containerized Environment with Spot Security

Designed for the cloud, Spot Security conducts agentless, real-time risk assessments to identify the most critical misconfigurations and vulnerabilities, based on the potential attack surface and cloud asset relationships.

With Spot Security, you can:

  • Gain a holistic view of your cloud environment using risk impact maps to uncover even minor security gaps that can put your organization’s crown jewels at risk.
  • Prioritize actionable insights with a single dashboard view based on the attack surface, risk severity and network exposure.
  • Create groups of business-critical assets and track their security posture, access, permissions, and compliance status in a single view.
  • Save time and effort by automating the remediation workflows with ready-to-use Python and CLI code.

Learn more about Spot Security to secure your containerized environment.