Achieving Kubernetes compliance requires a careful blend of technical controls, governance policies, and security best practices. To help you in this process, we have compiled an actionable guide for Kubernetes PCI compliance, NIST container security, and CIS Kubernetes benchmark. By leveraging these best practices and tools, organizations can confidently secure their Kubernetes environments and maintain regulatory compliance.
Kubernetes PCI Compliance
Achieving PCI compliance on Kubernetes requires a combination of network segmentation, strong encryption, role-based access control, and robust monitoring. Here’s an overview of how Kubernetes can meet PCI DSS compliance requirements.
1. Network Segmentation (Requirement 1)
2. Encryption of Cardholder Data (Requirement 3)
PCI DSS Requirement: Cardholder data must be encrypted when stored and transmitted over public networks.
Kubernetes Solution:
Use Kubernetes Secrets to manage sensitive data such as encryption keys and passwords securely.
Ensure that data stored on persistent volumes is encrypted using tools like AWS EBS encryption or GCP Cloud KMS.
Implement mutual TLS (mTLS) through a service mesh like Istio to secure communications between services.
Drawback: Kubernetes Secrets are stored in plaintext in etcd by default, so encrypting etcd or using an external vault service like HashiCorp Vault may be necessary.
3. Access Control (Requirements 7 and 8)
PCI DSS Requirement: Restrict access to cardholder data based on need-to-know, and assign unique IDs to every person with computer access.
Kubernetes Solution:
Role-Based Access Control (RBAC) can enforce the principle of least privilege by limiting access to resources based on user roles.
Tools like OPA (Open Policy Agent) and Kubernetes Pod Security Policies (or Kyverno) can enforce strict access controls at the API level.
Integrate Identity-Aware Proxy (IAP) solutions like Pomerium to manage secure access based on identity and context.
Drawback: Misconfigurations in RBAC or policy management can lead to overprivileged access, compromising compliance.
4. Monitoring and Logging (Requirement 10)
PCI DSS Requirement: Track and monitor all access to network resources and cardholder data.
Kubernetes Solution:
Implement audit logging in Kubernetes to capture all administrative and API access events. Kubernetes Audit Logs can be shipped to external logging platforms like Elasticsearch or Splunk for analysis.
Use Prometheus and Grafana to monitor the health of clusters and set up alerts for suspicious activity.
Falco can be used to detect anomalous behavior at runtime, ensuring that unauthorized access attempts are flagged.
Drawback: Logs can be overwhelming without a centralized and well-structured log management solution, making it difficult to ensure complete coverage.
5. Vulnerability Management (Requirement 6)
PCI DSS Requirement: Develop and maintain secure systems and applications.
Kubernetes Solution:
Implement container image scanning using tools like Trivy, Aqua Security, or Clair to detect vulnerabilities in application images before they are deployed.
Keep Kubernetes clusters up-to-date with the latest patches, especially in critical security components like the control plane and etcd.
Use policy engines like OPA Gatekeeper to enforce security rules on container images, ensuring that only trusted and scanned images are deployed.
Drawback: Patch management can be difficult, especially in production clusters, where downtime must be minimized.
6. Testing Security Controls (Requirement 11)
7. Physical Security (Requirement 9)
PCI DSS Requirement: Restrict physical access to cardholder data.
Kubernetes Solution:
For self-hosted Kubernetes clusters, ensure that the physical security of the data center hosting the Kubernetes nodes adheres to PCI requirements.
For cloud-based Kubernetes solutions, leverage the physical security assurances provided by cloud providers (AWS, GCP, Azure) which are typically PCI compliant.
Drawback: When using cloud providers, you're relying on their assurances and compliance, so review their PCI DSS Attestation of Compliance (AoC).
8. Incident Response (Requirement 12)
PCI DSS Requirement: Maintain a policy that addresses information security and incident response.
Kubernetes Solution:
Implement an incident response plan that includes procedures for isolating compromised workloads, investigating security incidents, and restoring affected systems.
Use container snapshots and backups to quickly restore services in the event of a breach.
Drawback: Developing a comprehensive incident response plan requires thorough documentation and training of your team.
Cost Considerations
Cloud Provider Costs: Using managed services (e.g., GKE, EKS, or AKS) can reduce some operational burdens but may introduce additional costs for advanced security features (e.g., network security, IAM integration).
Security Tools: Tools like Pomerium (Free, or $7/user/month), Aqua Security, Sysdig Secure, or Twistlock can add significant costs but provide deep container security features necessary for PCI compliance.
Operational Overhead: Maintaining compliance may require additional staff or resources, especially to manage policies, logging, and incident response.
CIS Kubernetes Benchmark
In this guide, we’ll explore the key areas of the CIS Kubernetes Benchmark, how to achieve compliance, and common tools used to automate and enforce these security measures.
1. Control Plane Configuration
The Kubernetes control plane consists of several critical components such as the API server, etcd, the scheduler, and the controller manager. The CIS Benchmark provides recommendations on how to secure these components to prevent unauthorized access and vulnerabilities.
Common Tools:
2. Etcd Security
etcd is the key-value store used by Kubernetes to store all cluster data. Protecting etcd is critical because it holds sensitive information like secrets, configurations, and the state of the cluster.
Encryption: Ensure that data in etcd is encrypted at rest by configuring encryption for sensitive data.
Access Control: Limit access to etcd only to the control plane components, and enforce TLS client certificate authentication for etcd communications.
Network Segmentation: Ensure that etcd is placed in a separate network segment to reduce attack surfaces and minimize the risk of unauthorized access.
Common Tools:
3. Control Plane Authentication and Authorization
To ensure secure access to the Kubernetes API, the CIS Benchmark recommends a layered approach to authentication and authorization.
Authentication: Use OIDC (OpenID Connect) or another secure authentication provider to verify user identity.
Authorization: Implement RBAC to limit user and service account permissions. Make sure that roles are assigned according to the principle of least privilege.
Admission Controllers: Enable security-focused admission controllers like NodeRestriction, AlwaysPullImages, and PodSecurityPolicy (deprecated, now replaced by alternatives like Kyverno or OPA Gatekeeper).
Common Tools:
4. Pod Security Policies and Runtime Security
While PodSecurityPolicy has been deprecated, CIS still recommends enforcing stringent security policies at the pod level to ensure that containers are running with the least privilege necessary.
Container Privileges: Avoid running containers as root and ensure that containers are restricted from accessing the host network or file system unless necessary.
Security Contexts: Configure the security context of pods to control privileges like user/group IDs and access capabilities.
Runtime Policies: Use tools like AppArmor or SELinux to enforce mandatory access control at runtime.
Common Tools:
5. Logging and Monitoring
Logging and monitoring are crucial to maintaining visibility into the cluster’s operation and detecting potential threats.
Audit Logs: Enable audit logging on the API server to track all access and actions performed. Configure logs to capture enough detail to allow for a full audit trail.
Logging Aggregation: Use log aggregation tools like Elasticsearch, Fluentd, and Kibana (EFK Stack) to centralize and analyze logs. Monitoring tools like Prometheus and Grafana can provide real-time metrics and alert on cluster activity.
Runtime Security: Tools like Falco monitor runtime activity for suspicious or anomalous behavior, such as containers attempting to run privileged commands.
Common Tools:
6. Network Policies
The CIS Kubernetes Benchmark emphasizes the importance of controlling network traffic within the cluster. Network policies define how pods communicate with each other and with external systems.
Segmentation: Use Kubernetes Network Policies to restrict pod-to-pod and pod-to-external traffic. This is especially important to isolate sensitive workloads (e.g., payment services, databases) from general application traffic.
Ingress/Egress Control: Ensure that you have clear ingress and egress policies in place to limit the attack surface and prevent unauthorized network access.
Common Tools:
7. Cluster Role and User Access Management
Managing and auditing access to the cluster is key to maintaining a secure environment. CIS emphasizes strict control of role-based access, ensuring that users and services are only granted necessary privileges.
Service Accounts: Restrict the use of default service accounts and ensure that each application has its own dedicated service account with limited permissions.
User Accounts: Regularly review RBAC roles and bindings to ensure that users have only the necessary access to perform their jobs.
Common Tools:
8. Security Benchmarks and Continuous Compliance
Once compliance with CIS benchmarks is achieved, it’s important to maintain continuous compliance by regularly auditing and checking the cluster for deviations.
Regular Audits: Schedule regular audits of your Kubernetes clusters using tools like kube-bench to ensure that configurations remain in line with CIS recommendations.
CI/CD Integration: Integrate CIS checks into your CI/CD pipelines to catch non-compliant deployments before they reach production.
Common Tools:
Cost Considerations
Tooling Costs: Some tools, such as Aqua Security and Sysdig Secure, offer CIS compliance checks and may come at a premium but provide additional layers of automation and security.
Operational Costs: Maintaining continuous compliance requires regular audits, which may require additional resources or services to ensure ongoing adherence to the benchmark.
Cloud Providers: Managed Kubernetes services (e.g., GKE, EKS, AKS) often come with built-in compliance tools but may have higher costs compared to self-managed clusters.
NIST Container Security Compliance
Here’s a detailed breakdown of the key security considerations, controls, and best practices from the NIST SP 800-190 document.
1. Threats to Containerized Applications
NIST SP 800-190 outlines several categories of threats that containerized environments face:
Image Vulnerabilities: Containers are built from images, which can contain vulnerabilities if outdated or unpatched software is included. Attackers may exploit these weaknesses to compromise the application or host system.
Untrusted Images: Using third-party or public images without verification introduces risks since these images may contain malicious code or backdoors.
Runtime Exploits: During execution, containers may be attacked through exposed APIs, network vulnerabilities, or application bugs.
Host OS and Kernel Exploits: A compromised container may attempt to break out of its isolation and exploit vulnerabilities in the host operating system or kernel, leading to full system compromise.
Improper Isolation: Misconfigured containers can lead to privilege escalation, allowing attackers to move laterally across containers or access sensitive resources on the host system.
2. Container Lifecycle Security
NIST emphasizes securing the entire container lifecycle, which consists of image creation, deployment, and runtime phases.
a. Image Creation and Build Phase
Security Threats:
Security Controls:
Image Scanning: Use image scanning tools (e.g., Clair, Trivy) to identify known vulnerabilities in container images before deploying them.
Minimal Base Images: Build images from minimal base images to reduce the attack surface. Avoid unnecessary software in the image.
Digital Signatures: Sign images using tools like Docker Content Trust or Notary to ensure integrity and authenticity.
b. Image Deployment Phase
Security Threats:
Security Controls:
Policy Enforcement: Use tools like Open Policy Agent (OPA) or Kyverno to enforce security policies on image deployment. For instance, only trusted, signed images should be allowed to run in production.
Immutable Images: Make images immutable to prevent changes after deployment. This ensures that only pre-verified images are used.
Limit Resource Access: Use Kubernetes' resource quotas and pod security policies to limit access to system resources and privileges during deployment.
c. Runtime Phase
Security Threats:
Containers may be attacked while running, or they may access sensitive resources.
A compromised container may break out of its isolation and affect other containers or the host system.
Security Controls:
Runtime Monitoring: Use tools like Falco to monitor containers for abnormal behavior and runtime anomalies. This helps detect potential attacks or compromises at runtime.
Least Privilege: Ensure that containers run with the least privileges necessary. Avoid running containers as root, and restrict access to system resources using security contexts with advanced tools like Pomerium.
Network Isolation: Use network policies to isolate containers from each other unless communication is necessary. Network segmentation helps prevent lateral movement if one container is compromised.
3. Container Orchestration Security
Orchestration platforms like Kubernetes are essential for managing containers at scale, but they also introduce security challenges that need to be addressed.
a. Kubernetes Security Configuration
Threats:
Security Controls:
RBAC (Role-Based Access Control): Implement strict RBAC policies to limit access to the Kubernetes API server and other critical components. Each service and user should only have the permissions they need.
Secure Kubernetes Components: Use encryption for communication between Kubernetes components (e.g., API server, etcd) and secure etcd data at rest.
Pod Security Standards: Use Pod Security Admission (PSA) to enforce pod security standards across the cluster.
b. Securing Service Mesh and Network Policies
Threats:
Security Controls:
Service Mesh: Use a service mesh like Istio or Linkerd to manage secure, encrypted communication between microservices. Service meshes also provide traffic control, policy enforcement, and mutual TLS (mTLS) between services.
Network Policies: Define Kubernetes Network Policies to control which pods can communicate with each other or external networks. This limits the potential attack surface.
4. Securing Container Host and Infrastructure
Even though containers are isolated, they still share the same kernel and resources of the host operating system. Therefore, securing the container host is essential to preventing breakout attacks.
a. Host Operating System Hardening
Threats:
Security Controls:
Minimal OS: Use a minimal operating system designed for container environments, such as CoreOS or Bottlerocket, which reduces the number of packages and the attack surface.
Kernel Hardening: Enable security modules like AppArmor or SELinux to provide additional control over what containers can do on the host system. These can help prevent containers from escaping or accessing sensitive files.
Regular Patching: Ensure that the container host and its kernel are regularly patched to protect against known vulnerabilities.
b. Container Runtime Security
Threats:
Security Controls:
Trusted Runtimes: Use trusted and secure container runtimes like containerd or CRI-O instead of Docker to reduce the attack surface. These runtimes are purpose-built for Kubernetes and are often lighter and more secure.
Runtime Sandboxing: Use sandboxing solutions like gVisor or Kata Containers to provide an additional layer of isolation between containers and the host.
5. Logging and Monitoring
Continuous monitoring and logging are critical to detecting and responding to security incidents in a containerized environment.
Log Aggregation: Use centralized logging solutions like EFK Stack (Elasticsearch, Fluentd, Kibana) or Loki to collect and analyze logs from containers, orchestration platforms, and the host system.
Real-time Alerts: Set up real-time alerts using tools like Prometheus and Grafana to monitor system health, performance, and security incidents.
Security Events: Monitor container security events with tools like Falco and Sysdig Secure, which can detect suspicious behavior and unauthorized access attempts.
6. Supply Chain Security
NIST SP 800-190 highlights the importance of securing the container supply chain to prevent compromised or malicious images from entering the system.
Image Source Verification: Ensure that container images come from trusted sources. Avoid downloading images from unverified public repositories.
Image Scanning: Continuously scan images for vulnerabilities before deploying them in production. This ensures that all components and dependencies are free from known exploits.
Image Signing: Use image signing to verify the integrity and authenticity of images. This ensures that only signed and trusted images are deployed.
7. Incident Response
In the event of a security incident, having a well-defined incident response plan is critical for minimizing damage and restoring operations.
Forensic Analysis: Use container-aware forensic tools to analyze compromised containers and hosts.
Backup and Recovery: Implement regular backups of container images, data, and configurations to ensure fast recovery in case of an incident.
Isolate Compromised Containers: Immediately isolate and stop compromised containers to prevent further damage. Tools like Kubernetes Pod Disruption Budgets can help control the process of stopping compromised containers.
Wrapping up
In conclusion, achieving Kubernetes compliance across PCI DSS, CIS Benchmarks, and NIST SP 800-190 requires implementing strong security controls throughout the cluster lifecycle. From network segmentation to runtime security and continuous monitoring, aligning with these frameworks ensures a secure, compliant environment. Tools like Pomerium play a critical role by offering identity-aware access control, ensuring only authorized users can access sensitive services and data. This helps organizations meet compliance requirements around access control, auditing, and secure communication.
