15 Kubernetes Security Best Practices You Must Know

What Are Kubernetes Security Best Practices? 

Kubernetes security aims to protect Kubernetes clusters, its resources, and the applications running within it, from unauthorized access and attacks. Kubernetes security best practices span across pre-deployment, deployment, and runtime phases, encompassing the entire lifecycle of containerized applications. By implementing these guidelines, organizations can ensure their Kubernetes environment is resilient against threats.

The recommendations include secure configurations, applying the principle of least privilege, regular updates, and integrating security tools. Ensuring security in a Kubernetes environment requires a proactive approach, including regular vulnerability scanning, enforcing network policies, and monitoring activity.

This is part of a series of articles about container security.

Learn about the following Kubernetes security best practices:

Pre-Deployment Security Best Practices

Here are some best practices for ensuring security in the pre-deployment phase:

1. Secure CI/CD Pipelines and Container Images

Securing CI/CD pipelines is vital to prevent unauthorized changes and ensure the integrity of code and container images being deployed. This includes restricting access to the pipeline, verifying code integrity through digital signatures, and scanning images for vulnerabilities. Automated security checks should be integrated into the pipeline to detect issues early.

Container images should also be scanned for vulnerabilities before deployment. There are multiple tools that can analyze images against known vulnerabilities, recommending fixes before they’re deployed. This proactive approach reduces the surface area for potential attacks.

2. Use Minimal Base Images

Minimal base images contain only the essential components needed for an application to run, reducing the potential attack surface. By using smaller images, you limit the number of packages and vulnerabilities that can be exploited. 

This practice encourages the creation of lightweight, efficient containers that are less prone to security issues. Building images from minimal bases also improves deployment speed and efficiency. With fewer components to update and patch, maintaining security becomes simpler. 

3. Use Trusted Sources for Base Images

Sourcing base images from trusted registries is crucial to ensure their integrity and security. Trusted sources, like Docker’s official images or those from major cloud providers, are regularly scanned and maintained against vulnerabilities. Using these trusted sources reduces the risk of introducing malware or exploitable vulnerabilities into your environment.

It’s also important to verify the provenance (source) of images by using signing and validation tools. Ensuring the authenticity of an image before pulling it into your environment helps to maintain security throughout the supply chain.

4. Host Operating System Hardening

It is important to harden the operating system for hosts used to run Kubernetes nodes. This involves configuring the operating system to minimize vulnerabilities and reduce potential attack vectors—for example, applying security patches, disabling unnecessary services, and enforcing security policies. Regularly updating the operating system and installed packages is also critical for mitigating risks.

It is also recommended to use minimal OS versions specifically designed for running containers, such as CoreOS, Flatcar Container Linux, or Red Hat Enterprise Linux Atomic Host. These versions are optimized for security and performance in containerized environments, offering additional layers of protection.

5. Regularly Update Component Versions

Keeping Kubernetes components and dependencies up-to-date is essential for security. Updates often address vulnerabilities and enhance security features, reducing the risk of exploitation. However, take into consideration that Kubernetes upgrades can be complex and time-consuming. 

In addition, regularly reviewing third-party open source components and their licenses can also prevent security and compliance issues. This can be automated using tools like software composition analysis (SCA).

Deployment Security Best Practices

Here are some best practices for ensuring security in the deployment phase:

6. Implement Namespaces

Namespaces in Kubernetes enable multi-tenancy by isolating resources within the cluster. Using namespaces, administrators can limit the scope of resources, applying security controls and policies on a per-namespace basis. This isolation reduces the risk of unauthorized access across different project environments. However, it’s important to note that namespace isolation, on its own, is not strongly enforced and can be bypassed by attackers.

Implementing namespaces correctly involves associating network policies, role-based access controls (RBAC), and resource quotas to each namespace. This structured approach enhances security by providing a logical separation of concerns within the cluster.

7. Apply Network Policies

By default, pods can communicate freely within a Kubernetes cluster. Network policies in Kubernetes control the flow of traffic between pods and external endpoints, enforcing a zero-trust network model. Applying strict network policies limits connections, reducing the attack surface. Defining ingress and egress rules based on the principle of least privilege blocks unwanted traffic flowing into and out of the cluster.

Effective network policies require understanding application communication patterns. Administrators should document and regularly review these patterns to ensure policies remain relevant and secure.

8. Restrict Permissions to Secrets

Kubernetes secrets store sensitive information such as passwords and tokens. Restricting permissions to secrets is crucial to prevent unauthorized access. Using Kubernetes RBAC, access can be finely grained, allowing only specific roles or pods access to secrets.

Encrypting secrets at rest and in transit further enhances security. While Kubernetes supports encryption at rest natively, external key management systems can offer additional security layers.

9. Assess Container Privileges

Limiting container privileges ensures that even if an attacker compromises a container, their ability to cause harm is minimized. Running containers as non-root users and restricting kernel capabilities are effective strategies. Security contexts can enforce these restrictions cluster-wide.

Regularly assessing and adjusting container privileges, based on the principle of least privilege, reduces the potential impact of a security breach. This ongoing process involves collaboration between security teams and developers to balance security with functionality.

10. Integrate Security Tools with Kubernetes Clusters

Integrating security tools such as vulnerability scanners and runtime security monitoring solutions enhances Kubernetes security. These tools can detect anomalies, scan for vulnerabilities, and enforce policy compliance in real time. Integration should be seamless, offering visibility without impacting performance.

Selecting tools that are specifically designed or can adapt to Kubernetes environments ensures more effective security coverage. These tools should complement Kubernetes’ built-in security features, providing a layered defense strategy.

Learn more about securing Kubernetes with Spot Security.

Runtime Security Best Practices

Here are some best practices for ensuring security in the production phase:

11. Encrypt Data in Transit

Encrypting data in transit protects it from interception and unauthorized access as it moves between services or to external systems. TLS encryption should be implemented for all communications within the Kubernetes cluster and for ingress and egress traffic. Automated certificate management simplifies the encryption process, ensuring certificates are valid and up-to-date.

Using service meshes like Istio or Linkerd can also automate encryption, providing mutual TLS (mTLS) between services. While service mesh can be complex to implement, once in place, it significantly enhances security with minimal configuration, ensuring data confidentiality across the cluster.

12. Use Intrusion Detection and Prevention Tools

Intrusion detection and prevention tools monitor network and system activities for malicious actions or policy violations. In Kubernetes environments, these tools should be capable of understanding container- and Kubernetes-specific events. This allows for the detection of unusual patterns that could indicate a security threat.

Configuring these tools to automatically block or alert on suspicious activities helps in proactively protecting the environment. Integration with incident response workflows ensures quick reaction to potential threats, minimizing impact.

13. Automate Compliance Reports

Automating compliance reporting simplifies the process of demonstrating adherence to regulatory standards and security policies. Tools that can evaluate Kubernetes configurations against best practices and compliance requirements save time and reduce human error. Regularly scheduled audits ensure continuous compliance.

Reports should include a comprehensive view of the environment, identifying non-compliant configurations and suggesting remediations. This continuous feedback loop helps maintain high security and compliance standards.

14. Aggregate Logs and Metrics by Pods

Aggregating logs and metrics at the pod level provides insights into the behavior and performance of containerized applications. This information is crucial for detecting anomalies and optimizing resources. Tools like Fluentd and Prometheus can collect, aggregate, and analyze data, offering visibility across the Kubernetes environment.

Efficiently managing these large datasets requires robust storage and analysis solutions. Implementing a proper logging and monitoring strategy enables quick troubleshooting and informed decision-making, enhancing operational security.

15. Use Threat Intelligence

Threat intelligence involves using external data about threats and vulnerabilities to enhance security. Integrating this information into Kubernetes security practices can preemptively protect against known exploits and attack vectors. Tools that compare real-time cluster activity against threat databases offer proactive defense mechanisms.

Regularly updating threat intelligence and tuning systems based on new information keeps defenses current. Collaboration with external threat intelligence communities further enhances the ability to anticipate and mitigate potential security events.

Secure Kubernetes Clusters 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 Kubernetes clusters.