Azure Kubernetes Security Best Practices

Securing your Azure Kubernetes Service (AKS) clusters is paramount to protecting your applications and data. This guide outlines key security best practices and considerations for AKS environments.

Network Security

Control traffic flow into and out of your AKS cluster and pods.

• Network Policies

  Implement Kubernetes Network Policies to restrict network access between pods. This follows the principle of least privilege, allowing only necessary communication.

  apiVersion: networking.k8s.io/v1
  kind: NetworkPolicy
  metadata:
    name: deny-all-ingress
    namespace: default
  spec:
    podSelector: {}
    policyTypes:
    - Ingress

• Azure Network Security Groups (NSGs)

  Use NSGs at the subnet level to filter traffic to and from AKS nodes. This provides an additional layer of network segmentation.

• Azure Firewall / Application Gateway

  Deploy Azure Firewall or Application Gateway for advanced traffic filtering, WAF (Web Application Firewall) capabilities, and centralized network security management.

• Private Clusters

  Consider using AKS private clusters to restrict direct access to the Kubernetes API server from the public internet.

• Ingress Controllers with TLS

  Always use TLS encryption for ingress traffic. Configure your ingress controller to use certificates managed by Azure Key Vault for better security and lifecycle management.

Identity and Access Management

Secure access to your AKS cluster and resources.

• Azure Active Directory Integration

  Integrate AKS with Azure AD for centralized user authentication and authorization. This allows you to manage Kubernetes RBAC using Azure AD groups.

• Role-Based Access Control (RBAC)

  Configure Kubernetes RBAC roles and role bindings meticulously. Grant only the necessary permissions to users and service accounts. Avoid granting cluster-admin privileges unnecessarily.

• Service Accounts

  Use dedicated service accounts for applications running in the cluster and grant them the minimum required permissions via RoleBindings.

Secrets Management

Protect sensitive information like API keys, passwords, and certificates.

• Azure Key Vault Integration

  Store and manage all secrets in Azure Key Vault. Integrate AKS with Key Vault using the CSI Secrets Store driver or by mounting secrets as volumes.

  apiVersion: secrets-store.csi.x-k8s.io/v1
  kind: SecretProviderClass
  metadata:
    name: azurekeyvault-inline
    namespace: default
  spec:
    provider: azure
    parameters:
      usePodIdentity: "false"
      useVMManagedIdentityExtension: "true"
      keyvaultName: "your-keyvault-name"
      objects: |
        - objectName: "mysecret"
          objectType: "secret"
          secretName: "your-secret-name"
      tenantId: "your-tenant-id"

• Avoid Storing Secrets in Git

  Never commit secrets directly into your source code repositories.

Image Security

Ensure the integrity and security of container images used in your cluster.

• Container Image Scanning

  Regularly scan container images for vulnerabilities using tools like Azure Security Center or third-party scanners before deploying them to AKS.

• Trusted Registries

  Use trusted container registries, such as Azure Container Registry (ACR), and configure image pull secrets to ensure only authorized images can be pulled.

• Minimal Base Images

  Use minimal, hardened base images to reduce the attack surface.

• Immutable Images

  Treat containers as immutable. Avoid running commands or making changes inside a running container.

Runtime Security

Monitor and protect your applications while they are running.

• Pod Security Policies (Deprecated) / Pod Security Admission

  Use Pod Security Admission (PSA) or previously Pod Security Policies (PSPs) to enforce security standards for pods at creation time. Configure profiles like `Restricted` or `Baseline`.

• Security Context

  Configure `securityContext` for pods and containers to restrict privileges, such as running as non-root, disabling privilege escalation, and dropping capabilities.

  securityContext:
    runAsNonRoot: true
    readOnlyRootFilesystem: true
    allowPrivilegeEscalation: false

• Network Segmentation within Pods

  While Network Policies handle inter-pod communication, consider application-level security within pods if necessary.

Monitoring and Auditing

Gain visibility into cluster activity and detect security incidents.

• Azure Monitor for Containers

  Enable Azure Monitor for Containers to collect and analyze logs and performance metrics from your AKS cluster, including container logs and audit logs.

• Kubernetes Audit Logs

  Configure and collect Kubernetes audit logs. Analyze these logs for suspicious activities, unauthorized access attempts, and configuration changes.

• Azure Security Center

  Leverage Azure Security Center for continuous security monitoring, threat detection, and recommendations across your AKS environment.

• Alerting

  Set up alerts in Azure Monitor or Azure Security Center for critical security events.

Policy Enforcement

Automate security and compliance policies.

• Azure Policy for AKS

  Use Azure Policy to enforce organizational standards and assess compliance at scale. This can restrict configurations like allowing privileged containers, insecure capabilities, or disallowing specific image registries.

• OPA Gatekeeper

  For more advanced and dynamic policy enforcement, consider deploying OPA Gatekeeper as an admission controller.

Data Encryption

Protect data at rest and in transit.

• Storage Encryption

  Ensure that persistent volumes used by AKS are encrypted at rest using Azure Disk Encryption or Azure Storage Service Encryption.

• TLS for Communication

  As mentioned earlier, enforce TLS for all external and internal communication where sensitive data is transmitted.

By implementing these best practices, you can significantly enhance the security posture of your Azure Kubernetes Service deployments.