Runtime Security

Runtime security monitors and protects your containers and applications while they’re running. Unlike preventive measures (like RBAC or network policies), runtime security detects and responds to threats in real-time as they occur. Think of it as a security guard watching your application 24/7, ready to alert you or take action when something suspicious happens.

What is Runtime Security?

Runtime security operates during the execution phase of your workloads:

flowchart TD A[Container Starts] --> B[Runtime Security Active] B --> C{Monitor Behavior} C --> D{Suspicious Activity?} D -->|Yes| E[Alert/Block] D -->|No| F[Continue Monitoring] F --> C E --> G[Security Team Notified] style A fill:#e1f5ff style B fill:#fff4e1 style E fill:#ffebee style G fill:#ffebee

Why Runtime Security Matters

Preventive security (RBAC, network policies, hardening) is essential, but it’s not enough:

Zero-day vulnerabilities - New attacks that bypass preventive controls
Insider threats - Authorized users doing malicious things
Configuration drift - Security settings that change over time
Application-level attacks - Attacks targeting application logic, not infrastructure

Runtime security provides visibility and protection when preventive measures fail.

Types of Runtime Security

1. Behavioral Detection

Monitors system calls, file access, and network activity to detect anomalies:

Unusual process execution
Suspicious file access patterns
Abnormal network connections
Privilege escalation attempts

2. Policy Enforcement

Enforces security policies at runtime:

Blocks prohibited system calls
Prevents unauthorized file access
Restricts network connections
Stops privilege escalation

3. Threat Intelligence

Correlates events with known attack patterns:

MITRE ATT&CK framework mapping
Known malware signatures
Attack pattern recognition
Threat actor behavior

Runtime Security Tools

Falco

Open-source runtime threat detection that monitors system calls and container behavior. Detects:

Shell execution in containers
Unauthorized file access
Network anomalies
Privilege escalations

KubeArmor

Policy-based runtime protection using eBPF. Enforces:

File system access controls
Network restrictions
Process execution limits
Capability restrictions

eBPF-based Solutions

Leverage eBPF for efficient, low-overhead security monitoring:

Real-time system call monitoring
Network packet inspection
Process and file tracking
Minimal performance impact

How Runtime Security Works

sequenceDiagram participant App as Application participant Kernel as Linux Kernel participant Runtime as Runtime Security participant Alert as Alerting System App->>Kernel: System Call Kernel->>Runtime: Event Captured Runtime->>Runtime: Analyze Behavior alt Suspicious Activity Runtime->>Alert: Send Alert Runtime->>Kernel: Block Action (optional) else Normal Activity Runtime->>Kernel: Allow end Kernel-->>App: Response

Integration with Kubernetes

Runtime security tools integrate with Kubernetes through:

DaemonSets - Deploy agents on every node
CRDs - Define security policies as Kubernetes resources
Webhooks - Integrate with admission control
Operators - Manage security policies automatically

Best Practices

Deploy on all nodes - Use DaemonSets for complete coverage
Start with detection - Begin with monitoring, then add enforcement
Tune rules carefully - Avoid false positives that overwhelm teams
Integrate with SIEM - Send alerts to security information systems
Regular rule updates - Keep detection rules current
Performance monitoring - Ensure runtime security doesn’t impact workloads

Common Use Cases

Detecting Cryptocurrency Miners

Monitor for:

High CPU usage patterns
Network connections to mining pools
Unusual process execution
Resource consumption anomalies

Preventing Data Exfiltration

Detect and block:

Large file transfers
Unauthorized network connections
Database access from unexpected sources
Suspicious data access patterns

Stopping Lateral Movement