Overview of the 4C’s
The 4C’s of cloud-native Kubernetes security are four concentric layers. Each inner layer depends on the security of the layers surrounding it.Cloud
Security of the cloud infrastructure hosting the Kubernetes clusters — public or private cloud, data centers, and network firewalls that prevent unauthorized remote access.
Cluster
Security of the Kubernetes cluster through authentication, authorization, admission controls, and network policies — including the Docker daemon.
Container
Security of containers: restricting untrusted images, securing the supply chain, using sandboxed containers for isolation, and avoiding privileged containers.
Code
Security of the application code running inside containers. Developers must follow code security best practices to prevent vulnerabilities.
Cloud provider security
The cloud provider is responsible for the security of the physical infrastructure (hardware, software, networking, and facilities), while the customer is responsible for managing network and firewall settings, data, applications, identity and access management, and operating systems. This is known as the Shared Responsibility Model. To secure the cloud layer:- Activate the network firewall — permit or deny traffic based on source/destination IP, port, and protocol to prevent unauthorized access.
- Follow the Shared Responsibility Model — understand the division of responsibilities between provider and customer.
- Use Cloud Provider Security Capabilities across three categories:
Threat detection tools
Threat detection tools
| Provider | Tool | Description |
|---|---|---|
| AWS | GuardDuty | Uses machine learning to detect threats |
| GCP | Security Command Center | Centralized dashboard to monitor threats and security health |
| Azure | Microsoft Sentinel | Combines SIEM and SOAR for automated threat detection and response |
Application firewall tools
Application firewall tools
| Provider | Tool | Description |
|---|---|---|
| AWS | AWS WAF | Protects web applications from SQL injection, XSS, and other exploits |
| GCP | Cloud Armor | DDoS protection and common attack mitigation |
| Azure | Azure WAF | Protects web applications from SQL injection, XSS, and other exploits |
Container security tools
Container security tools
| Provider | Tool |
|---|---|
| AWS | EKS, Bottlerocket, kube-bench (CIS benchmarks) |
| GCP | GKE, Anthos, Open Policy Agent (OPA) |
| Azure | AKS |
Cluster security
Server hardening is the process of enhancing server security through a series of steps.- Isolate applications on separate servers or networks to reduce the risk of cross-contamination.
- Use firewall rules and policies to restrict Docker port access.
- Apply least privilege to containers and secure the Kubernetes dashboard using RBAC to eliminate vulnerabilities.
- Store sensitive data in Kubernetes Secrets.
- Encrypt ETCD data at rest and use TLS for secure communication between Kubernetes components. Set RBAC and perform regular backups.
Kubernetes isolation techniques
- Namespaces — Isolate resources for multiple teams or environments (multitenancy). Different teams and projects can use the same cluster without interfering with each other.
- Network Policies — Control traffic flow between pods by allowing or denying traffic based on source and destination.
- RBAC (Role-Based Access Control) — Control access to cluster resources by granting or denying access based on roles and permissions.
- Resource Quotas — Limit the amount of resources a namespace can consume to prevent resource exhaustion or monopolization.
- Pod Security Policies — Control pod security settings by enforcing security contexts such as running containers as non-root, disallowing privilege escalation, and restricting host namespace access.
Artifact repository and image security
- Use an Artifact Repository (e.g., Artifactory, Nexus) to store container images securely.
- Scan container images for vulnerabilities before deploying (e.g., Trivy, Clair).
- Use trusted or minimal base images (e.g., Alpine Linux) to reduce the attack surface. Reputable sources perform regular updates and security scans.
- Use digital signatures to verify container image authenticity and integrity.