What Is Container Security? Risks, Solutions, and Best Practices

Containers are lightweight, standalone, executable software packages that include everything needed to run a piece of software. They play a central role in modern DevOps and software development processes. 

While containers provide many advantages over traditional software deployment methods, they also introduce new security risks. Some of these risks stem from the fact that containers operate on a shared operating system and threats can spread between containers if they are not properly isolated. Other risks stem from the use of container images, which might contain security vulnerabilities or malicious components, to create large numbers of containers.

Container security encompasses the practices, strategies, and tools designed to protect containerized applications from unauthorized access and vulnerabilities. The scope of container security spans the entire container lifecycle, from the creation and build process through deployment and runtime, to their eventual shutdown. Containers have a much shorter lifespan than traditional software, adding another layer of complexity to securing them.

In light of these challenges, specialized security practices and solutions have emerged for securing containers. These can comprehensively address vulnerabilities within the container’s images, the container runtime environment, and the orchestration platforms that manage the containers’ deployment and scaling.

In this article:

The Importance of Container Security 

The security of containers has a direct impact on the security of software applications and the underlying infrastructure. Containers offer a high level of portability and efficiency, allowing developers to quickly deploy applications across various environments. 

However, this agility comes with risks, as containers can be targeted by attackers to exploit vulnerabilities, leading to data breaches, service disruptions, and compromised systems. Ensuring container security thus becomes essential for maintaining the integrity, confidentiality, and availability of applications and data.

The widespread adoption of containers in DevOps practices necessitates robust security measures. As containers promote faster deployment cycles and more dynamic scaling of applications, they must be secured to prevent vulnerabilities from being introduced during rapid development and deployment processes. 

Common Container Security Challenges and Risks 

Here are some of the main challenges involved in securing containerized applications.

Distributed and Dynamic Environments

Containers often run across multiple hosts and clouds, increasing the attack surface and complexity of securing these environments. Ensuring consistent security policies and practices across all environments is difficult, leading to potential gaps in protection.

The dynamic scaling of containerized applications can also complicate security monitoring and management. As containers are frequently started and stopped on demand, maintaining visibility and control over security across the entire distributed architecture requires sophisticated tools and strategies.

Short Container Lifespan

Containers are designed to be ephemeral and short-lived, creating challenges for security monitoring and incident response. Traditional security tools and approaches may not be effective in environments where containers are constantly being created and destroyed. It is also more challenging to detect and analyze security incidents, as the evidence may no longer exist once the container is terminated.

Adapting security strategies to account for the ephemeral nature of containers involves implementing real-time monitoring and centralized logging solutions. These tools must be capable of quickly identifying and responding to threats, even in rapidly changing environments, and able to centrally store and analyze logs even after containers shut down.

Unsafe or Malicious Container Images

The proliferation of container images, often sourced from public repositories, raises significant security concerns. Not all images are vetted for security, and they may contain vulnerabilities or even malicious code. Ensuring the integrity and security of container images thus becomes paramount. 

Strategies to mitigate these risks include the use of private registries, pre-deployment image scanning for vulnerabilities and malware, and implementing digital signature verification to ensure image authenticity. Additionally, the adoption of tools that can continuously monitor and scan images for newly discovered vulnerabilities helps maintain the security posture of containerized applications over time.

Risk of Open Source Components

Many containerized applications rely on open-source components, which can introduce security risks if not properly managed. Vulnerabilities in these components can be exploited by attackers to compromise containers and the applications they host. 

Ensuring the security of open-source components involves using secure coding practices, regularly scanning container images for known vulnerabilities and updating components to secure versions. The vulnerability management process should include continuous monitoring for new vulnerabilities, and patching of affected components.

Compliance Requirements

Containers must be configured and managed to meet the requirements of regulations such as GDPR, HIPAA, and PCI DSS. This involves implementing controls to protect sensitive data, ensuring data privacy, and maintaining audit trails of container activity.

Navigating the complex landscape of compliance requirements requires a thorough understanding of the specific regulations applicable to the organization’s operations. A major challenge is that many compliance standards do not have explicit guidance for containers, and some of their security requirements were designed for traditional deployment models, and are difficult to apply in a containerized environment.

Components of Container Security 

Securing containers requires securing the following components:

Registry Security

Registries or repositories are where container images are stored before deployment. A secure registry ensures that images are scanned for vulnerabilities, signed to verify their integrity, and only accessible to authorized users. This prevents the use of compromised or malicious images that could undermine the security of the entire containerized application.

Implementing robust access controls and audit logs for the container registry helps track who accessed or modified an image, further enhancing security. Regularly scanning images for vulnerabilities and updating them ensures that the applications are protected against known threats, making registry security a critical first line of defense in container security.

Runtime Security

Runtime security involves securing containers when they are running on host systems. This includes monitoring container activity for suspicious behavior, enforcing runtime policies that restrict container access to host resources, and isolating containers to prevent one compromised container from affecting others. 

Runtime security tools can detect and prevent unauthorized access, network attacks, and exploitation of vulnerabilities within the running containers. Implementing least privilege access controls and network segmentation at runtime further strengthens container security. This ensures that containers have only the necessary permissions and network access required for their specific functions, minimizing the potential impact of a security breach.

Orchestration Security

The orchestration layer provides centralized control over containers, making it a target for attackers. It manages container lifecycles using tools like Kubernetes. Orchestration security involves securing the orchestration platform itself, ensuring secure communication between its components, and enforcing policies that control container deployment, scaling, and management. 

Best practices include using role-based access control (RBAC) to limit access to the orchestration platform, encrypting data in transit and at rest, and regularly updating the orchestration tools to protect against known vulnerabilities. 

Network Security

Attackers often seek to exploit the network connections within the containerized environment and between containers and external networks. Implementing network policies that define how containers communicate with each other and with external services is essential. This includes controlling ingress and egress traffic and isolating sensitive components using network segmentation.

Encrypting network traffic using protocols like TLS can prevent data interception and ensure that communication between containers and services remains confidential. Regular monitoring of network activity can also detect and respond to suspicious patterns, safeguarding the container ecosystem from network-based threats.

Storage Security

It’s essential to secure the data and storage mechanisms used by containerized applications. This includes protecting persistent storage volumes attached to containers and ensuring data integrity and confidentiality. Implementing encryption for data at rest, access controls for storage resources, and secure backup mechanisms are key aspects of storage security.

Integrating storage security solutions that support container environments can help detect and prevent unauthorized access to data. Regularly auditing access to storage resources and employing data encryption can significantly enhance the security of containerized applications’ data.

Environment Security

Lastly, it’s important to secure the infrastructure and networks that containers operate within. This includes securing the host operating system, implementing firewalls, implementing robust access control, and using secure communication protocols. Additionally, regular security assessments and adherence to best practices in infrastructure management can prevent potential security incidents.

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

Types of Container Security Solutions  

Fortunately, there are several types of security solutions available that can protect container-based applications.

Container Monitoring Solutions

Container monitoring solutions provide visibility into the performance, health, and security of containerized applications. They track container metrics, logs, and events in real-time, enabling the detection of security incidents and performance issues. 

By offering insights into container behavior, monitoring tools help detect anomalies and potential threats, such as unexpected network connections or abnormal resource usage.

Container Scanners 

Container scanning tools scan images for known security issues, misconfigurations, and compliance violations before and after deployment. By providing detailed reports on identified vulnerabilities, container scanners help developers and security teams address security risks before they can be exploited. 

Regularly scanning container images as part of the CI/CD pipeline ensures that security is integrated into the development process. 

Learn more in our detailed guide to container security scanning (coming soon)

Container Networking Tools

Container networking tools are essential for creating, managing, and enforcing networking policies in a containerized environment. These tools help define how containers communicate with each other and with external networks, crucial for isolating and securing container traffic. 

Networking tools can enforce network segmentation, manage ingress and egress rules, and ensure that containers operate within their designated network parameters. They also integrate with container orchestrators like Kubernetes to help automate networking policies.

Cloud Native Security Solutions

There are several types of cloud native security solutions that take a holistic approach to securing modern computing environments. For example: 

  • Cloud Native Application Protection Platforms (CNAPP) provide a unified security model that covers the entire application lifecycle, from development to runtime, integrating various security aspects like posture management, workload protection, and compliance monitoring. 
  • Cloud Workload Protection Platforms (CWPP) focus specifically on protecting workloads across different environments, including containers, virtual machines, and serverless functions. They offer capabilities such as vulnerability management, runtime protection, and network security, tailored to the dynamic and distributed nature of cloud-native workloads.

Related: Learn more in our guide on Kubernetes security best practices

6 Container Security Best Practices 

Here are some of the best practices for securing containerized applications.

1. Enforce Least Privilege

Applying the principle of least privilege ensures that containers and containerized applications have only the minimum levels of access or permissions needed to perform their functions. This approach limits the potential damage that can be done if a container is compromised. 

For instance, a container that only needs to read data from a specific database should not have write permissions. Enforcing least privilege can significantly reduce the attack surface within a containerized environment.

2. Using Thin, Short-Lived Containers

Utilizing thin, short-lived containers aligns with the microservices architecture principle, promoting the deployment of lightweight containers that perform a single function and can be easily replaced. 

Thin containers significantly reduce the attack surface, because they have less components and configurations that can be targeted by attackers. Short-lived containers minimize the time window for potential attacks, reducing the risk of successful exploits.

3. Use Minimal Images

Using minimal images for containers is a critical security practice. Minimal images contain only the essential binaries and libraries needed to run the application, reducing the risk of including vulnerabilities or unnecessary software that could be exploited by attackers. 

This practice not only improves security by minimizing the potential attack vectors but also enhances performance by reducing the size and startup time of containers. Regularly updating these minimal images to include the latest security patches is essential for maintaining a strong security posture.

4. Use Immutable Deployments

Immutable deployments are a key security and operational practice where deployed containers are never updated or modified in place but are replaced with new containers when changes are needed. This approach prevents configuration drift and ensures that the deployed environment remains consistent and predictable. 

Immutable deployments reduce the risk of unauthorized changes or tampering with running containers, as any modifications require deploying a new container version. This practice also simplifies rollback and enhances reliability since previous versions of containers can be quickly reinstated if needed.

5. Use TLS to Secure Communication Between Services

Using Transport Layer Security (TLS) to encrypt communication between services is essential for protecting sensitive data in transit. TLS ensures that data exchanged between containers and services cannot be intercepted or tampered with by malicious actors. 

Implementing TLS can prevent man-in-the-middle attacks and eavesdropping, safeguarding the confidentiality and integrity of data. Configuring services to use TLS certificates, ideally from a trusted certificate authority, helps in establishing a secure communication channel in a containerized environment.

6. Use Open Policy Agent (OPA)

The Open Policy Agent (OPA) is an open-source, general-purpose policy engine that enables unified, context-aware policy enforcement across the entire stack. Using OPA for container security allows organizations to define fine-grained, high-level policies that govern how, when, and by whom containers can be deployed, accessed, and managed. 

OPA integrates with the Kubernetes ecosystem, providing a powerful tool to enforce security policies at the deployment phase and runtime, ensuring compliance with organizational policies and regulatory standards. This approach not only enhances security but also promotes compliance and governance across containerized environments.

Learn more in our detailed guide to container security best practices

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.