Securing Containers and Kubernetes in a DevSecOps Pipeline

As businesses continue to embrace containerization and the use of Kubernetes for their cloud-native applications, the imperative to secure these technologies has become increasingly important. Containers play a crucial role in providing consistency, scalability, and efficiency for deploying applications across various environments. They enable developers to package their applications along with all their dependencies, ensuring that they can run seamlessly, regardless of where they are deployed. On the other hand, Kubernetes stands out with its robust orchestration capabilities, which are essential for managing a large number of containers at scale. This orchestration allows for automated deployment, scaling, and operational management of these containerized applications. Nevertheless, the surge in the adoption of containerization and Kubernetes does not come without challenges. With the expansion of these technologies within organizations, there is an equally significant increase in the necessity for comprehensive security measures to protect them. As more businesses rely on these systems for critical operations, understanding and implementing security best practices becomes paramount to safeguard applications from potential threats.

A Business Research Insight’s survey of Kubernetes and container technology adoption showed that:

• The global kubernetes solutions market size was valued at USD 2.14 billion in 2023 and is projected to touch USD 8.9 billion by 2032, exhibiting a CAGR of 17.3% during the forecast period.

The global container technology market size was valued at USD 496.4 million in 2021 and is expected to reach USD 3123.42 million by 2031, exhibiting a CAGR expansion of 19.8% during the forecast period.

The integration of DevSecOps – where security is integrated into every part of the development lifecycle -helps address the unique security challenges posed by containers and Kubernetes. In this blog, we’ll explore how to secure containers and Kubernetes within a DevSecOps pipeline, focusing on best practices, common challenges, and the tools and techniques you can use to build a secure and resilient infrastructure.

Why Containers and Kubernetes Require Special Attention?

Containers and Kubernetes: The Risks

Containers allow applications to run consistently across different environments, whether in development, testing, or production. Kubernetes automates container deployment, scaling, and management, making it ideal for managing cloud-native applications. However, these benefits also bring new security concerns:

• Container Image Vulnerabilities: Containers are often built using base images, which may contain vulnerabilities or outdated components.
• Kubernetes Configuration Issues: Kubernetes is complex, and improper configurations can expose sensitive data or lead to privilege escalation.
• Lack of Visibility: The ephemeral and dynamic nature of containers makes it difficult to maintain full visibility into container activities and network communications. This lack of visibility can hinder the detection of malicious activities and compromise response times.
• Secrets Management: Containers and Kubernetes rely heavily on sensitive data such as API keys, passwords, and tokens, which, if not managed securely, can lead to significant breaches.

Evolving Threat Landscape:

Attackers are increasingly exploiting misconfigurations within Kubernetes clusters, which can lead to unauthorized access and data breaches.

For instance, in 2024, A recently patched high-severity vulnerability in Kubernetes could enable a malicious attacker to execute remote code with elevated privileges under certain conditions.

Akamai security researcher Tomer Peled stated, “The vulnerability allows remote code execution with SYSTEM privileges on all Windows endpoints within a Kubernetes cluster. To exploit it, an attacker must apply malicious YAML files to the cluster.”(Source: Researchers Detail Kubernetes Vulnerability That Enables Windows Node Takeover)

Another significant threat involves the use of malware specifically designed for container environments. In 2021, security researchers discovered a new strain of malware called “Kinsing” that targeted exposed Kubernetes APIs to deploy cryptocurrency mining operations. This malware showcased how threat actors could exploit vulnerabilities in containers to gain financial benefits. The incident underscored the importance of securing container registries and API endpoints to prevent unauthorized access and exploitation. (Source: Kinsing malware targets Kubernetes environments via misconfigured PostgreSQL)

Lastly, threat actors are actively exploiting critical vulnerabilities in OpenMetadata to gain unauthorized access to Kubernetes workloads and leverage them for cryptocurrency mining activity. According to the Microsoft Threat Intelligence team, the flaws have been weaponized since the start of April 2024. OpenMetadata is an open-source platform that operates as a metadata management tool, offering a unified solution for data asset discovery, observability, and governance.(Source: Hackers Exploit OpenMetadata Flaws to Mine Crypto on Kubernetes)

Addressing these threats requires a multi-faceted approach, including enhanced security policies, employee training, and continuous monitoring of Kubernetes environments. As the threat landscape continues to evolve, staying informed and adapting security strategies accordingly will be crucial for organizations utilizing Kubernetes and containerization technologies.

So, To mitigate these risks, security must be a fundamental consideration throughout the entire DevSecOps pipeline.

DevSecOps: Embedding Security Across the SDLC

DevSecOps integrates security into every stage of the software development lifecycle (SDLC), specifically in our case for containerized applications and Kubernetes environments—from planning and coding to testing, building, and deploying. The objective is to shift security left by identifying and resolving vulnerabilities early in the process. By embedding security practices into the CI/CD pipeline for containers, teams can automate security checks such as image vulnerability scanning, compliance assessments, and runtime protection. This approach not only reduces the attack surface but also ensures that vulnerabilities are detected and mitigated before they reach the production environment, enhancing the overall security posture of containerized applications.

Best Practices for Securing Containers and Kubernetes

To secure containers and Kubernetes in a DevSecOps pipeline, organizations must follow several key best practices:

1. Image Security and Vulnerability Scanning

• Static Analysis of Dockerfile: Static analysis of a Dockerfile involves scanning it for security issues, misconfigurations, and best practice violations without actually building the image. This helps identify potential risks early in the development process.
• Scan for Vulnerabilities: One of the most critical steps in securing containers is ensuring the integrity of the images. Vulnerabilities in container images can be exploited if they aren’t detected before deployment. Tools like Trivy, Clair, and Anchore automate vulnerability scanning of container images, checking for known CVEs (Common Vulnerabilities and Exposures).
• Use Immutable Images: Ensure images are tagged immutably (e.g., v1.0.0) and avoid using “latest” in production.
• Use Trusted Base Images: Always opt for trusted and minimal base images. Minimal images, such as Alpine Linux, contain fewer components and thus reduce the attack surface. Additionally, ensure that all images are pulled from trusted registries.
• Image Signing and Verification: Use Docker Content Trust (DCT) to sign your container images. This ensures that only trusted, verified images are deployed to production, preventing unauthorized or compromised images from being used.

2. Runtime Security

• Use Security Profiles: Security profiles such as Seccomp, AppArmor, and SELinux help control what actions a container can perform at the kernel level. These profiles can prevent containers from performing dangerous actions like making system calls that could compromise the host system.
• Runtime Monitoring: Once containers are deployed, runtime monitoring is essential to detect abnormal or malicious activities. Tools like Falco and Sysdig Secure can help identify suspicious container activity by monitoring system calls and container behaviors in real-time.

3. Securing CI/CD Pipelines

• Automate Security Checks: Integrate automated security scans into the CI/CD pipeline to ensure that code and container images are free from vulnerabilities before they are deployed to production. Tools like SonarQube and Snyk can scan source code for vulnerabilities, while Trivy can scan container images for issues.
• Enforce Security Policies: Use policy enforcement tools like OPA (Open Policy Agent) to define and enforce security policies across the pipeline. This ensures that only secure, compliant code and container images make it through the pipeline.
• Continuous Monitoring and Logging: Monitor the pipeline for any unusual activities and ensure that logs are captured for auditing purposes. Continuous monitoring tools like Prometheus and Datadog can provide real-time insights into your container environment.

4. Securing Kubernetes Clusters

While containers provide the environment for running applications, Kubernetes is the orchestration platform that manages those containers. Securing a Kubernetes cluster requires attention to both its infrastructure and its runtime components.

• Role-Based Access Control (RBAC): Properly configure RBAC to ensure that users and services only have the permissions necessary to perform their tasks. Misconfigured RBAC can lead to privilege escalation or unauthorized access to sensitive resources.
• Least Privilege Principle: Always follow the least privilege principle—grant users and services only the minimum permissions they need to function.
• Pod Security: Implement PodSecurityPolicies or use Pod Security Admission to enforce rules, such as running containers as non-root and disallowing privileged containers. you should also leverage namespaces to isolate workloads.
• Network Policies: Kubernetes allows you to define Network Policies to restrict traffic flow between pods. By applying network segmentation, you can minimize the risk of lateral movement in case of a security breach. For example, you can configure network policies to only allow communication between specific services and restrict traffic to/from external sources.
• Secrets Management: Kubernetes provides a built-in mechanism to store sensitive data such as API tokens and passwords using Kubernetes Secrets. However, it’s important to ensure that secrets are encrypted at rest and that access is tightly controlled. Integrating external secrets management systems like HashiCorp Vault or AWS Secrets Manager can add an additional layer of security.
• Enable Cloud Policy: Implementing cloud policy across various cloud platforms ensures compliance and integrates with the platform’s security features, such as network security tools and firewalls. It helps to enforce best practices and security rules throughout your cloud resources, enhancing governance and risk management in your environment.
• Kubernetes Hardening: Regularly audit the cluster and apply security hardening practices to reduce the attack surface. Use tools like kube-bench and kube-hunter to check the security posture of your Kubernetes cluster and ensure compliance with security best practices.
• Enable Resource Constraints: Limit CPU and memory usage for containers to prevent resource exhaustion as this configuration prevents a single container from consuming all the resources of a node, which could lead to a denial-of-service attack.
• Enable Comprehensive Monitoring: To enhance visibility into the health and performance of your containers, enable Container Insights, Prometheus metrics, and Managed Grafana. Set up recommended alert rules to monitor container performance and resource usage. This configuration will allow you to identify potential security incidents by tracking anomalies in container behavior and infrastructure, ensuring that your cluster remains secure and well-optimized.
• Enable OIDC and Workload Identity: Use OpenID Connect (OIDC) and Workload Identity to secure authentication and access for your Kubernetes workloads. These tools ensure that only authorized workloads can interact with the Kubernetes API, protecting sensitive resources from unauthorized access.
• Enable Image Cleaner: To improve security by reducing the attack surface, enable Image Cleaner to automatically remove outdated or unused container images. This reduces the potential for vulnerabilities that may exist in stale images and helps keep your image repository clean and secure.

5. Patching and Updates

• Regular Patching: Regularly patch both Kubernetes and the containers running within the cluster. Ensure that container images are built using the latest secure versions of base images, and update Kubernetes components to protect against known vulnerabilities.
• Monitor Vulnerabilities: Use automated tools to monitor vulnerabilities in the Kubernetes environment and the containers it orchestrates. Tools like KubeScan and Trivy help identify new vulnerabilities as they emerge and ensure that updates are applied promptly.

Tools for Securing Containers and Kubernetes

Several tools and platforms can help automate and enhance container and Kubernetes security within a DevSecOps pipeline:

• Hadolint, Snyk, and Checkov: Tools that identify security vulnerabilities, enforce best practices, and detect misconfigurations in Dockerfiles, ensuring secure and efficient container images.
• Trivy/Claire/Anchore: A simple, fast, and comprehensive container image vulnerability scanner.
• Falco: A runtime security tool for detecting suspicious behavior in containers and Kubernetes clusters.
• AppArmor/SELinux: Access control systems that restrict container capabilities and enforce security policies at the kernel level to safeguard against unauthorized actions.
• OPA (Open Policy Agent): A policy engine that helps define and enforce security policies across Kubernetes, containers, and the CI/CD pipeline.
• Kube-bench: A tool that checks the Kubernetes cluster against the CIS Kubernetes Benchmark for security best practices.
• Kube-hunter: A tool that audits the security posture of Kubernetes clusters.
• Aqua Security and Sysdig Secure: Comprehensive container and Kubernetes security platforms offering vulnerability scanning, runtime protection, and compliance checks.
• Infrastructure as Code (IaC) Security: Use tools like Checkov or Terraform Validator to secure Kubernetes manifests and infrastructure configurations.

Conclusion

Securing containers and Kubernetes within a DevSecOps pipeline is essential for developing robust, resilient, and secure applications in today’s cloud-native landscapes. By integrating security into every phase of the development lifecycle- ranging from image scanning and securing runtime environments to enforcing policies within the CI/CD pipeline- organizations can effectively mitigate risks and safeguard their infrastructure against vulnerabilities and attacks.

With the right tools, practices, and policies, a DevSecOps approach enables continuous security, ensuring that containerized applications remain secure from development through to production. By embracing a proactive and automated security strategy, teams can confidently build and deploy cloud-native applications.

A key takeaway is the importance of establishing a resilient and secure Kubernetes environment. Protecting Kubernetes is vital for defending containerized applications against emerging cyber threats. Organizations can significantly reduce the risk of security breaches by implementing strong access controls, securing network traffic, utilizing trusted images, and maintaining vigilant monitoring of their Kubernetes environments. As reliance on Kubernetes continues to escalate, adhering to best practices and leveraging advanced security solutions becomes crucial for maintaining a resilient and secure Kubernetes ecosystem.