GUEST POST
Author Gilad David Maayan
What is Kubernetes Security?
Kubernetes is an open source platform that helps you orchestrate Linux containers and manage microservices architecture across public, private, and hybrid clouds. Kubernetes involves deploying a cluster composed of different layers and services, such as worker nodes, pods, and containers. This complex architecture, which changes frequently as Kubernetes becomes a foundation for modern software deployment, creates a large, dynamic attack surface.
Kubernetes security involves implementing best practices and technologies to protect the Kubernetes platform, container images, configurations, and other of your containerized environments. You can use Kubernetes-native tools to address various security concerns, but in many cases, you will also need to integrate with third-party solutions to close security gaps. See this blog for more background about Kubernetes security.
Kubernetes Security Best Practices
1. Kubernetes Vulnerability Scanning
Kubernetes vulnerability scanners can help you identify and fix security issues in your Kubernetes deployments. These tools enable you to remediate vulnerabilities in the Kubernetes platform, container images, and Kubernetes configurations.
The Kubernetes platform
Kubernetes, like any open source project, is exposed to many security vulnerabilities. Learning about new vulnerabilities and implementing a process to quickly update Kubernetes with the latest versions and patches is critical to protect these workloads. Kubernetes vulnerability scanners ensure you run the latest Kubernetes version and update when important security patches are released.
Container images
Scanning container images is critical to protect applications. It helps ensure untested images are not used in production Kubernetes clusters or any other Kubernetes environment. Vulnerability scanners can identify open source components in container images and compare them against known vulnerabilities.
Kubernetes configurations
A robust vulnerability scanner should compare application architectures against Kubernetes’ best practices to identify misconfigurations and vulnerabilities. The scanner should also perform compliance scanning to inspect Kubernetes deployments for the compliance requirements relevant to the organization, including sensitive data confidentiality, secure configuration, and ingress/outgress data flows.
2. Enable Role-Based Access Control (RBAC)
RBAC enables you to control access to the Kubernetes API and restrict user permissions granularly. Kubernetes 1.6 and later versions come with RBAC enabled by default. To ensure RBAC works properly, you must disable the legacy attribute-based access control (ABAC). You can check your settings to see which option is enabled for your version of Kubernetes.
Here are RBAC best practices to consider:
Avoid cluster-wide permissions, and implement namespace-specific permissions instead.
Do not give any user cluster admin privileges—not even for debugging. Instead, grant access as needed and on a case-by-case basis.
For applications that need to access the Kubernetes API, you should create separate service accounts and assign them the least permissions required at each use site.
3. Implement Service Mesh
A service mesh implements an infrastructure layer dedicated to microservices applications. It handles infrastructure service communication securely, reliably, and quickly to reduce the complexity of managing microservices. Service meshes solve operational challenges and issues that occur when you run containers and microservices by providing a uniform way to monitor, secure, and connect microservices.
A service mesh provides tracing and telemetry metrics to help understand a system and quickly find the root cause of problems. It includes security features, such as ingress and egress controls and TLS, that protect services inside a network and identify compromising traffic that enters a cluster.
4. Leverage Kubernetes Monitoring Tools
Kubernetes provides an orchestrator and APIs that enable you to build and run various workloads. However, it cannot support production environments without additional tools. It relies heavily on configurations and third-party tools to achieve optimal security standards. Here are Kubernetes security tools to help monitor running workloads:
Behavioral analysis and network monitoring tools
Each application follows a certain pattern, but changes can cause it to deviate from the pattern. Common changes include a new version, going viral, a security breach, or a marketing campaign. To ensure timely mitigation of security breaches, you must understand these anomalies and their origins.
Logging and monitoring tools
A microservice platform utilizes many services that split container logs, and requests can move between different services. You need specialized tools to capture and store all these logs in a centralized environment. Monitoring and logging tools work differently in containers and Kubernetes, requiring processes built for containerized environments.
Networking and storage tools
Kubernetes does not provide built-in networking and storage tools. Instead, you can use plugins. Most distributions provide defaults and options to modify settings, such as adding a service mesh.
5. Implementing Open Policy Agent (OPA) for a Centralized Policy Management
OPA is an open source project that began in 2016. It aims to unify policy enforcement across various systems and technologies. You can use the OPA to enforce policies on various platforms, including Kubernetes clusters.
Kubernetes utilizes RBAC and pod security policies to perform fine-grained control over a cluster. However, these policies apply to the cluster only and do not work externally. OPA provides a unified method to enforce security policy across the stack. It includes authorization technology and a declarative policy language built especially for writing and enforcing rules.
OPA offers various tools to help integrate policies into applications and allow application end-users to contribute policies for their tenants. It integrates directly into the Kubernetes API and has complete authority to reject any resource the policy determines does not belong in the cluster, including networking, computing, and storage.
You can expose OPA policies early in the software development lifecycle (SDLC), including CI/CD pipelines and developer laptops, to get feedback during early phases. You can also run policies out-of-band to monitor your results and ensure policy changes do not inadvertently cause issues.
Conclusion
In this article, I explained the basics of Kubernetes security and provided a few critical best practices you should know to secure your clusters. Of course, it is not possible to cover all security best practices for such a complex system in a single post. To dive deeper into Kubernetes security, check out the CIS Kubernetes Security Benchmark, which provides a detailed list of everything you need to do to securely configure your Kubernetes clusters and nodes.