Mastering Containerization: Key Strategies and Best Practices

As organizations modernize their infrastructure, containers offer unparalleled flexibility and scalability but they also introduce unique security challenges. In this blog we explain container security challenges, identify top threats and share how the newly released Tenable Enclave Security can keep your containers secure.

Containers are changing enterprise IT and are now essential in modern app development. In my two decades as a cybersecurity practitioner, I have seen technologies evolve from offering efficiency to becoming vulnerable points of attack due to neglected security measures. Containers are no different. They provide unmatched flexibility and scalability, yet they also introduce specific vulnerabilities that, when not remediated, can weaken an entire organization's security posture.

The evolution of containers and the imperative of security

Containers have dramatically changed how organizations approach software development and deployment. Containers guarantee that software operates consistently in various environments by bundling an application and its dependencies into a single, transferable unit. This is a big change for development teams, enabling quick iteration and deployment. Yet, this flexibility introduces a complicated security environment that calls for a change in how organizations approach incorporating security into their development processes.

Containers, in contrast to traditional virtual machines, are lightweight, depend on the host operating system's kernel and frequently utilize shared images from both public and private registries. These interdependencies result in an environment in which a single weakness can lead to a series of consequences, highlighting the importance of container security as a vital necessity rather than just a recommended measure.

One base image can create thousands of attack points within an environment, so it is critically important to understand the base image vulnerabilities to reduce propagation to subsequent images.

Why security must begin at the container's creation

Benjamin Franklin said, "an ounce of prevention is worth a pound of cure," and this rings especially true in the context of containers. The security of a containerized environment hinges on decisions made at the very beginning of the container lifecycle — during the creation phase. Here’s why:

1. Avoiding the pitfalls of security debt: Security debt accumulates when vulnerabilities are embedded in container images from the start. As containers transition from development to production, addressing these vulnerabilities becomes increasingly difficult and more expensive, particularly in a fast-paced DevOps environment. By incorporating security measures such as automated vulnerability scanning and secure configuration management early on, you can prevent exposures from growing into larger, more complex issues that would require significant resources to resolve later on.
2. Mitigating supply chain threats: Containers often depend on a variety of third-party libraries and components, which can introduce vulnerabilities if not carefully vetted. By embedding security checks during the creation phase, including dependency scanning and verification, you reduce the risk of incorporating compromised or malicious code into your container images. This approach not only secures your own code but also fortifies the broader software supply chain.
3. Ensuring robust runtime security: The configurations designed during the creation of a container — including access controls, resource limits and network policies — directly influence its security posture at runtime. A container built with security in mind will be less susceptible to common attacks like privilege escalation or container escape, thereby reducing the attack surface and safeguarding the runtime environment.
4. Analyzing layers as a defensive strategy: Containers are constructed in levels called layers, with each one symbolizing a distinct step in the image formation process. This complex structure, although effective, may contain undisclosed weaknesses. Performing a comprehensive analysis of each layer is essential so you can recognize and address potential risks during each phase. By examining every layer, eliminating unnecessary parts and confirming that all layers are current and clear of identified vulnerabilities, you enhance the container's security as a whole. Consistently reviewing these layers in your security procedures helps prevent new vulnerabilities from being overlooked.
5. Setting the stage for continuous security monitoring: Early integration of security practices enables continuous monitoring throughout the container lifecycle. Taking a proactive approach enables immediate identification and response to threats, guaranteeing timely detection and resolution of potential vulnerabilities before they can be taken advantage of.

The high stakes of container attacks: what’s at risk?

Understanding the potential consequences of container breaches is essential to appreciating the importance of proactive security measures. Here’s a deep dive into some of the most pressing threats and their implications:

1. Image poisoning: Malicious actors can breach container images by injecting harmful code or exploiting weaknesses. This could happen at different stages of the supply chain, from vulnerable developer environments to public or private registries. What’s worse, after these toxic images are initially used in an attack, if not remediated, they can be re-used to launch more attacks, which can lead to consequences such as attackers gaining unauthorized entry and stealing data.
   • Consequences: Image poisoning creates an ease of persistence for attackers. If a container registry is compromised and an attacker is able to make changes to multiple containers, they can add code for persistent payloads, malware or exfiltration to the containers, which will then be run every time that container is launched. A poisoned image can lead to widespread compromise across multiple environments, particularly in organizations that rely on standardized images for deployment.
2. Runtime exploits: Containers, by design, have the same OS kernel shared, leaving them susceptible to kernel-level attacks when isolation is lacking. Malicious individuals can use these weaknesses to break out of the container, take over the host system and potentially reach other containers on the same host.
   • Consequences: A host system can be completely compromised through a successful runtime exploit, allowing attackers to move freely across the network. This could result in a complete breach, loss of data and disruption of essential services, causing lasting damage to an organization's operational stability.
3. Container escape: Container escape occurs when an attacker breaks out of a container’s isolated environment to execute code on the host system. This can happen due to misconfigurations, unpatched vulnerabilities or privilege escalation attacks.
   • Consequences: A breach in a container could put the entire host system at risk, leading to unauthorized access to important data and systems. The outcomes could be substantial, requiring comprehensive incident response actions and possibly resulting in regulatory penalties and loss of trust from customers.
4. Supply chain attacks: Containers frequently depend on external components, which makes them particularly vulnerable to supply chain attacks. These incidents involve attackers compromising dependencies or registry services in order to insert vulnerabilities into container images.
   • Consequences: Supply chain attacks are frequently discreet and are typically unnoticed until they have spread through various environments. Tracing and fixing the security breaches that occur can be difficult, which can prolong exposure to threats and disrupt operations significantly.

A checklist for securing containers

Securing containers requires a multi-faceted approach that addresses every stage of the container lifecycle. Five key strategies are listed below. For a comprehensive checklist review, read the white paper Checklist: Securing containers from development to runtime. 

1. Secure-by-design: Integrate security into the container development process from the onset. Use automated tools to scan for vulnerabilities and enforce secure configurations before containers are deployed.
2. Regular vulnerability scanning: There will always be new vulnerabilities. Embedding regular vulnerability scanning is a critical part of maintaining secure containers. Scans should be done on the image registry or as part of the CI/CD pipeline and, where vulnerabilities are found, images should be re-built and re-deployed. Automate patch management to ensure that vulnerabilities are addressed promptly and consistently.
3. Layer analysis: Conduct thorough layer analysis of container images. Scan each layer for vulnerabilities, remove unnecessary components and ensure that all layers are up-to-date. This process should be iterative, with regular re-evaluation to account for new threats. Regularly run searches for known malicious code against all image layers to identify compromises.
4. Prioritize vulnerabilities for remediation: Organizations can quickly lose control of security risks if vulnerabilities are not effectively prioritized. Choose a container security solution that uses threat intelligence to help you prioritize what to fix first. 
5. Use trusted base images: Only use base images from verified, trusted sources. Regularly scan these images for vulnerabilities and rebuild them frequently to incorporate security updates.

Securing containers with Tenable Enclave Security

We’re excited to announce Tenable Enclave Security, a new product designed to help highly secure environments expose and close IT and container vulnerabilities. 

Tenable Enclave Security enables you to quickly know the risk in your IT assets and container images, expose their vulnerabilities and understand their breadth of impact and close exposures using priority scores to speed remediation efforts. Tenable Enclave Security protects containers by embedding security from the start, making it easy for DevOps teams to quickly detect and fix container vulnerabilities before they hit production, conducting thorough analysis into all images, layers and packages that need attention, reducing risk and ensuring the integrity of your containerized environments. Vulnerability priority scores help you focus your efforts on the most critical vulnerabilities to reduce vulnerability overload and maximize productivity. 

Built specifically for highly secure environments, Tenable Enclave Security meets the needs of organizations with stringent cloud security and data residency requirements, such as those operating in classified or air-gapped environments, or federal agencies requiring FedRAMP High or Impact Level 5. Tenable Enclave Security helps government agencies meet key standards and guidelines for securing container environments such as National Institute of Standards and Technology (NIST) SP 800-190 and Center for Internet Security (CIS) Docker Benchmarks and CIS Kubernetes Benchmark. 

Conclusion

In the ever-changing realm of cybersecurity, containers bring about potential advantages as well as obstacles. Although containers foster flexibility and creativity, they also require a proactive and thorough security strategy. By integrating security at the beginning, carrying out comprehensive layer examination, and following established government guidelines, organizations can greatly lower their risk and protect the authenticity of their containerized setups.

Based on my experience, I have seen the outcomes of ignoring security measures. The organizations that prioritize security throughout the container lifecycle are the ones that will succeed in their efforts to embrace and use container technologies. As we progress in this world of containerization, let's stay alert, knowledgeable and steadfast in our dedication to securing the future of our systems.

For more information

• Join us for a webinar on Oct 17, 2024: Get Container Confident: Protecting Containers in High-Security Environments
• Checklist: Securing Containers from Development to Runtime
• Tenable Enclave Security Webpage