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Kubernetes Runtime Security: Foundation and Best Practices

Kubernetes runtime security refers to the measures and practices implemented to protect Kubernetes clusters and the applications running within them during their operational phase.

6 minutes read

What is Kubernetes Runtime Security?

Kubernetes plays a pivotal role in cloud infrastructure, as it seamlessly deploys, scales, and manages containerized apps. Its ability to orchestrate container deployment across a cluster of machines offers unparalleled efficiency and scalability. However, this complexity also introduces an expanded attack surface and security concerns that must be addressed to protect the container environment, especially in production environments.

Kubernetes runtime security protects applications and infrastructure from unauthorized access and security vulnerabilities during the execution phase of containers. It encompasses a broad range of security controls and practices to mitigate security risks associated with container runtimes, network policies, and the underlying host and kernel-level operations.

This blog post will explore Kubernetes runtime security, providing a comprehensive understanding of its importance, the challenges it addresses, and the best practices for securing Kubernetes environments.

Why is K8s runtime security important?

Runtime security in Kubernetes is not just an option but a critical requirement. It addresses security issues during the runtime phase of containerized applications, focusing on detecting and preventing unauthorized access, privilege escalation attacks, and other security threats. 

An effective runtime security strategy involves monitoring runtime environments, enforcing security policies, and utilizing runtime protection mechanisms to safeguard against potential threats.

Popular tools for Kubernetes runtime security

Ensuring robust Kubernetes runtime security involves a multi-layered approach addressing various environmental aspects. Prominent tools in this space help identify and mitigate security vulnerabilities, enforce security policies, and provide runtime protection. 

To operationalize your runtime security effectively, you should follow a structured approach consisting of the following action areas and their corresponding tools. 

Misconfiguration and vulnerability scanning: kube-bench and Kubescape

kube-bench is a go-to tool for assessing the security of Kubernetes clusters against the benchmarks established by the Center for Internet Security (CIS). It evaluates your Kubernetes configurations, ensuring they adhere to the best practices for securing K8s components and reducing the attack surface. 

Figure 1: kube-bench output (Source: GitHub)

Kubescape is a comprehensive tool for assessing the security posture of Kubernetes clusters. It scans for vulnerabilities, misconfigurations, and deviations from best practices, providing insights into potential security risks. 

Figure 2: Kubescape in action (Source: GitHub)

By integrating these tools into your Kubernetes security best practices, you can achieve a more secure and resilient Kubernetes environment, ready to tackle the challenges of the modern cloud infrastructure landscape.

Network security and service mesh: Calico

Calico is renowned for its network security capabilities within K8s environments. It enables developers to implement network policies that control traffic flow between pods, thereby segmenting the network and reducing the potential attack surface.

Figure 3: Network policy and communication in the cluster (Source: Microsoft Cloud Blog)

Policy management and enforcement: Open Policy Agent (OPA)

OPA provides a sophisticated declarative language for the creation and implementation of policies throughout a Kubernetes ecosystem. It integrates seamlessly with K8s, providing a unified toolset for managing security policies, admission control, and configuration validation. 

Figure 4: OPA overview (Source: OPA)

Real-time threat detection: Falco

Falco is an open-source project focusing on real-time threat detection within Kubernetes environments. It monitors container runtime behavior at the kernel level, detecting anomalous activity and potential security threats in real time.

Figure 5: Falco rules editor (Source: Sysdig Blog)

Best practices for Kubernetes runtime security

Securing Kubernetes environments requires a multifaceted approach, combining the use of powerful tools, discussed above, with robust security practices.

Regularly scan for vulnerabilities and misconfigurations

Regular audits of your Kubernetes environment are essential for maintaining a secure posture. By scanning your Kubernetes clusters, control planes and data planes, and containers, you can uncover vulnerabilities and misconfigurations that threat actors could exploit. 

Utilizing Kubernetes audit logs, admission controllers, and tools like Kubescape, you’ll be able to review actions taken within your clusters, identify potential security issues, and verify compliance with your security policies. 

These audits can reveal unauthorized access attempts, misconfigurations, and other security risks that require attention.

Figure 6: Kubescape scan output (Source: GitHub)

Implement network policies for controlled access

Network policies are a powerful mechanism for controlling traffic flow between pods in a Kubernetes cluster. By defining network policies, you can restrict communications to only those connections that are explicitly allowed, minimizing the attack surface and preventing lateral movement within your cluster. 

The following Calico network policy restricts inbound and outbound traffic for the "myapp" application, allowing communication only with specified trusted applications and external services, thereby enhancing the security of your Kubernetes environment:

apiVersion: projectcalico.org/v3
kind: NetworkPolicy
metadata:
  name: restrict-traffic
  namespace: production
spec:
  selector: app == "myapp"
  ingress:
    - action: Allow
      source:
        selector: app == "trustedapp"
  egress:
    - action: Allow
      destination:
        selector: app == "external-service"

Develop and enforce strong security policies

The foundation of Kubernetes runtime security lies in developing and enforcing comprehensive security policies. These should address access controls, resource limitations, network policies, and other components in your K8s ecosystem.

OPA plays a critical role in policy management within Kubernetes environments. By defining policies as code, you can automate the enforcement of security controls, making your security posture robust and scalable. 

The following OPA policy ensures that only container images from a specified trusted registry can be deployed, preventing unauthorized or potentially malicious images from being run in your environment:

package kubernetes.admission

deny[msg] {
  input.request.kind.kind == "Pod"
  not input.request.object.spec.containers[_].image.startsWith("trustedregistry/")
  msg = "Only images from trustedregistry/ are allowed."

Utilize runtime monitoring and threat detection

Kubernetes features a dynamic environment, making continuous monitoring critical to detecting and responding to runtime security threats in real time. This level of monitoring ensures that you're immediately aware of any unauthorized access attempts or other security concerns, enabling swift action to mitigate potential issues.

Integrating real-time threat detection tools like Falco with your security incident response protocols allows you to automate reactions to any threats discovered, such as isolating affected pods or triggering alerts to security teams.

Figure 7: Falco event and statistics overview (Source: Falco docs)

Manage container runtimes and images

Container runtime security is an essential aspect of Kubernetes runtime security. Ensuring that your container runtime environment is configured securely and is up-to-date can significantly reduce the risk of vulnerabilities. 

Container images are the foundation of your K8s applications, and securing these images is paramount. Implementing best practices for container image management can significantly enhance your security posture, such as scanning, signing, and verification:

# Scan an image for vulnerabilities
trivy image my-application:latest
# Sign a container image (using Cosign)
cosign sign -key cosign.key my-registry/my-application:latest
# Verify a signed image (using Cosign)
cosign verify -key cosign.pub my-registry/my-application:latest

All the above steps can greatly improve the protection of your containerized applications against security threats.

Wiz: A comprehensive solution for Kubernetes security

Cloud computing will continue to transform at a rapid pace. This means companies must make securing their Kubernetes environments a top priority. Wiz emerges as a pioneering force in this domain, offering a unified cloud security platform that transcends traditional security measures. 

With its robust prevention and response capabilities, Wiz empowers security, development, and DevOps teams to collaborate effectively, ensuring the swift and secure deployment of cloud applications.

Example of how Wiz adds runtime context to the blast radius analysis,

Wiz's security controls and strategies for Kubernetes runtime security

Wiz stands out for its ability to offer a wide array of security controls and strategies, effectively safeguarding Kubernetes environments against the security threats they face. 

Vulnerability management

Wiz excels in finding vulnerabilities across clouds and workloads, including VMs, serverless architectures, containers, and appliances. With Wiz, uncovering vulnerabilities across your clouds and workloads becomes effortless. Our tools scan VMs, serverless applications, containers, and appliances for vulnerabilities without the need for external scans or deploying agents.

Container & Kubernetes security

Wiz offers specialized security solutions for containers and Kubernetes, enabling organizations to build containerized apps without compromising on security. Our all-in-one platform ensures rapid and secure development, securing containers, K8s, and cloud environments from build-time to real-time and addressing vulnerabilities at every stage of the development life cycle.

Cloud threat detection and response

Wiz provides advanced monitoring and threat detection capabilities, which are crucial for container security. This feature allows organizations to detect and respond to threats in real time, ensuring continuous security monitoring and rapid response to potential incidents in their cloud environments. Real-time threat detection is vital to maintaining a robust security posture in dynamic cloud and containerized systems.

Comprehensive policy enforcement and compliance

With Wiz, organizations can maintain automated compliance against industry standards and benchmarks, such as PCI, GDPR, HIPAA, and CIS Benchmarks—this is essential for hardening Kubernetes clusters. Our automated compliance capabilities simplify the management of regulatory requirements, ensuring that security policies are consistently enforced across your Kubernetes environment.

Supply chain security

Wiz extends its security capabilities to the entire supply chain, from code to deployment. This ensures a comprehensive security approach, safeguarding not just operational environments but also the underlying code and processes that contribute to the development and maintenance of applications.

Wiz offers a transformative solution for you to better address complex Kubernetes environments. Its unified platform reduces risk and grants unmatched visibility and prioritization, fostering business agility. 

To explore how Wiz can revolutionize your Kubernetes security strategy, schedule a demo today and discover the future of cloud security.

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