Security

Security in Kubernetes is about protecting your cluster, workloads, and data from threats. Kubernetes provides many security features, but security requires a defense-in-depth approach—multiple layers of protection working together. Think of it like a castle: you need strong walls (network policies), guards at the gates (authentication), careful access control (authorization), and monitoring for threats (audit logs).

The Security Model

Kubernetes security follows a defense-in-depth strategy with multiple layers:

graph TB A[Defense in Depth] --> B[Authentication] A --> C[Authorization] A --> D[Network Security] A --> E[Pod Security] A --> F[Secrets Management] A --> G[Policy Enforcement] A --> H[Runtime Security] A --> I[Supply Chain Security] A --> J[Audit & Compliance] B --> B1[Who Are You?] C --> C2[What Can You Do?] D --> D1[Who Can Talk to Whom?] E --> E1[What Can Pods Do?] F --> F1[Protect Sensitive Data] G --> G2[Enforce Policies] H --> H1[Detect Threats] I --> I2[Secure Images] J --> J1[Track Everything] style A fill:#e1f5ff style B fill:#fff4e1 style C fill:#e8f5e9 style D fill:#f3e5f5 style E fill:#ffe1e1

Each layer provides protection, and together they create a comprehensive security posture.

Security Layers

Authentication (Who Are You?)

Authentication verifies the identity of users and applications:

graph LR A[User/Application] --> B{Authentication Method} B --> C[Certificates] B --> D[Service Accounts] B --> E[OIDC] B --> F[Tokens] C --> G[Authenticated Identity] D --> G E --> G F --> G style A fill:#e1f5ff style G fill:#e8f5e9

Certificates - X.509 certificates for user authentication
Service Accounts - Identities for applications running in pods
OIDC - OpenID Connect for integration with identity providers
Tokens - Bearer tokens for API access

Authorization (What Can You Do?)

Authorization determines what authenticated entities can do:

graph TB A[Authenticated Request] --> B[RBAC Evaluates] B --> C{Has Permission?} C -->|Yes| D[Request Allowed] C -->|No| E[Request Denied] B --> F[Check Roles] B --> G[Check RoleBindings] B --> H[Check Resource] B --> I[Check Action] style A fill:#e1f5ff style D fill:#e8f5e9 style E fill:#ffe1e1

RBAC - Role-Based Access Control defines permissions
Roles - Namespace-scoped permissions
ClusterRoles - Cluster-wide permissions
RoleBindings - Grant roles to users or groups

Network Security (Who Can Talk to Whom?)

Network security controls pod-to-pod communication:

graph TB A[Pod A] --> B{Network Policy} B -->|Allowed| C[Pod B] B -->|Denied| D[Traffic Blocked] E[Default Deny] --> F[Explicit Allow Rules] F --> G[Ingress Rules] F --> H[Egress Rules] style A fill:#e1f5ff style C fill:#e8f5e9 style D fill:#ffe1e1 style E fill:#fff4e1

Network Policies - Firewall rules for pods
TLS - Encrypt traffic between services
Service Mesh - Advanced network security with mTLS

Pod Security (What Can Pods Do?)

Pod security restricts what containers can do:

graph TB A[Pod Security] --> B[Security Context] A --> C[Pod Security Standards] A --> D[Capabilities] A --> E[Seccomp/AppArmor] B --> F[Run as Non-Root] B --> G[Read-Only Root FS] B --> H[Drop Capabilities] style A fill:#e1f5ff style B fill:#e8f5e9 style C fill:#fff4e1

Security Context - Container-level security settings
Pod Security Standards - Baseline, restricted, and privileged policies
Capabilities - Linux capabilities that containers can use
Seccomp/AppArmor - System call and access restrictions

Secrets Management (Protect Sensitive Data)

Secrets store sensitive information securely:

graph TB A[Secrets] --> B[Encryption at Rest] A --> C[Encryption in Transit] A --> D[External Secrets] B --> E[etcd Encryption] C --> F[TLS] D --> G[Vault/AWS Secrets Manager] style A fill:#e1f5ff style B fill:#e8f5e9 style C fill:#e8f5e9 style D fill:#fff4e1

Kubernetes Secrets - Built-in secret storage
Encryption at Rest - Encrypt secrets in etcd
External Secrets - Integrate with external secret managers

Policy Enforcement (Enforce Policies)

Policy enforcement ensures compliance with security policies:

graph TB A[Policy Enforcement] --> B[Admission Webhooks] A --> C[OPA Gatekeeper] A --> D[Kyverno] B --> E[Validate Resources] C --> F[Open Policy Agent] D --> G[Kubernetes Native Policies] style A fill:#e1f5ff style B fill:#e8f5e9 style C fill:#fff4e1 style D fill:#f3e5f5

Admission Webhooks - Validate and mutate resources before creation
OPA Gatekeeper - Policy engine for Kubernetes
Kyverno - Kubernetes-native policy engine

Runtime Security (Detect Threats)

Runtime security monitors for threats and anomalies:

graph TB A[Runtime Security] --> B[Falco] A --> C[KubeArmor] A --> D[eBPF Monitoring] B --> E[Threat Detection] C --> F[System Call Monitoring] D --> G[Kernel-Level Visibility] style A fill:#e1f5ff style B fill:#e8f5e9 style C fill:#fff4e1 style D fill:#f3e5f5

Falco - Runtime threat detection
KubeArmor - System call enforcement
eBPF - Kernel-level monitoring

Supply Chain Security (Secure Images)

Supply chain security ensures container images are safe:

graph TB A[Supply Chain Security] --> B[Image Scanning] A --> C[Image Signing] A --> D[SBOM] B --> E[Vulnerability Detection] C --> F[Sigstore/Cosign] D --> G[Software Bill of Materials] style A fill:#e1f5ff style B fill:#e8f5e9 style C fill:#fff4e1 style D fill:#f3e5f5

Image Scanning - Detect vulnerabilities in images
Image Signing - Verify image authenticity
SBOM - Track software components

Audit & Compliance (Track Everything)

Audit logging tracks all API access for compliance:

graph TB A[API Request] --> B[Audit Log] B --> C[Who] B --> D[What] B --> E[When] B --> F[Result] C --> G[User/Service Account] D --> H[Resource & Action] E --> I[Timestamp] F --> J[Allowed/Denied] style A fill:#e1f5ff style B fill:#e8f5e9

Audit Logs - Record all API access
CIS Benchmarks - Security configuration standards
Policy Logs - Track policy enforcement

Security Lifecycle

Security is an ongoing process:

graph TD A[Plan Security] --> B[Implement Controls] B --> C[Monitor & Detect] C --> D{Threat Detected?} D -->|No| C D -->|Yes| E[Respond] E --> F[Remediate] F --> G[Review & Improve] G --> B style A fill:#e1f5ff style B fill:#e8f5e9 style C fill:#fff4e1 style E fill:#ffe1e1 style F fill:#e8f5e9

Plan - Define security requirements and policies

Implement - Deploy security controls (RBAC, Network Policies, Pod Security)

Monitor - Continuously monitor for threats and anomalies

Detect - Identify security incidents

Respond - Take action to contain threats

Remediate - Fix vulnerabilities and improve security

Review - Learn from incidents and improve

Security Best Practices

Principle of Least Privilege - Grant only the minimum permissions needed
Enable RBAC - Use Role-Based Access Control for all access
Use Network Policies - Implement network segmentation with Network Policies
Secure Pods - Run containers as non-root, drop capabilities, use read-only filesystems
Encrypt Secrets - Enable encryption at rest for etcd
Scan Images - Scan container images for vulnerabilities before deployment
Sign Images - Use image signing to verify authenticity
Enable Audit Logging - Track all API access for compliance
Use Admission Controllers - Validate and enforce policies at admission time
Monitor Runtime - Use runtime security tools to detect threats
Keep Updated - Regularly update Kubernetes and components
Harden Nodes - Secure the underlying nodes and operating systems

Common Security Patterns

Multi-Tenant Isolation

Isolate different teams or applications:

Namespaces for logical separation
Network Policies for network isolation
RBAC for access control

Zero-Trust Networking

Default deny, explicit allow:

Network Policies deny all by default
Explicit allow rules for needed communication
Service mesh mTLS for encrypted communication

Least Privilege Service Accounts

Applications run with minimal permissions:

Dedicated ServiceAccount per application
Minimal RBAC permissions
No cluster-admin access

Defense in Depth

Multiple security layers:

Authentication + Authorization
Network Policies + Pod Security
Policy Enforcement + Runtime Security

Topics

Authentication & Authorization

Authentication & Authorization - How users and applications authenticate
- Service Accounts - Identities for applications
- OIDC - OpenID Connect integration
RBAC - Role-Based Access Control
- Roles & Bindings - Defining and granting permissions
- Least Privilege - Implementing least privilege

Secrets Management

Secrets - Managing sensitive data
- Encryption at Rest - Encrypting secrets in etcd
- External Secrets - Integrating with external secret managers

Network Security

Network Security - Securing network communication
- Network Policies - Pod-level firewalls
- TLS - Transport Layer Security

Pod Security

Hardening - Securing pods and containers
- Security Context - Container security settings
- Capabilities - Linux capabilities
- Seccomp & AppArmor - System call restrictions

Policy Enforcement

Admission Controllers - Validating and mutating resources
- Pod Security Standards - Built-in pod security policies
- Webhooks - Custom admission logic
Policy Enforcement - Enforcing security policies
- OPA Gatekeeper - Open Policy Agent
- Kyverno - Kubernetes-native policies
- Patterns - Common policy patterns

Runtime Security

Runtime Security - Detecting threats at runtime
- Falco - Threat detection
- KubeArmor - System call enforcement
- eBPF - Kernel-level monitoring

Supply Chain Security

Supply Chain Security - Securing the software supply chain
- Image Scanning - Vulnerability detection
  - Trivy - Comprehensive scanner
  - Grype - Fast vulnerability scanner
  - Snyk - Developer-focused security
- Sigstore - Image signing and verification
  - Cosign - Container signing
  - Fulcio & Rekor - Certificate and transparency

Scanning & Assessment

Scanning - Security assessment tools
- Kubescape - Kubernetes security scanner
- Polaris - Configuration validation
- Checkov - Infrastructure as code scanning

Audit & Compliance

Audit - Tracking and compliance
- Audit Logging - API access logging
- CIS Benchmarks - Security configuration standards
- Policy Logs - Policy enforcement tracking