Tetragon 0.1: eBPF-Based Security Observability and Enforcement

Introduction

On May 10, 2022, Cilium released Tetragon 0.1, the first version of an eBPF-based security observability and runtime enforcement platform for Kubernetes. Built on eBPF, Tetragon provides real-time visibility into system calls, process execution, and network activity, enabling security teams to detect threats and enforce policies at the kernel level.

Traditional security tools rely on agents, log analysis, or post-incident forensics. Tetragon takes a different approach: it uses eBPF to observe security-relevant events directly in the kernel, providing real-time detection and enforcement without the overhead of traditional security agents.

Why Tetragon?

• Kernel-Level Visibility: eBPF programs observe security events at the source, not through logs.
• Real-Time Detection: Identify threats as they happen, not after the fact.
• Policy Enforcement: Block malicious activity using eBPF-based enforcement.
• Low Overhead: Kernel-level processing minimizes performance impact.

Core Capabilities

Process Execution Monitoring

• Process Lifecycle: Track process creation, execution, and termination.
• Binary Analysis: Identify which binaries are executed and by whom.
• Parent-Child Relationships: Map process trees to understand execution chains.
• Container Context: Associate processes with Kubernetes pods and containers.

System Call Observability

• Syscall Tracking: Monitor system calls for security-relevant operations.
• File Access: Track file opens, reads, writes, and deletions.
• Network Activity: Observe socket creation, connections, and data transfers.
• Privilege Escalation: Detect attempts to gain elevated privileges.

Network Security

• Connection Tracking: Monitor network connections and data flows.
• DNS Monitoring: Track DNS queries and responses for threat detection.
• Protocol Analysis: Identify suspicious network protocols or patterns.
• Policy Enforcement: Block unauthorized network connections.

Architecture

• Tetragon Agent: Runs as a DaemonSet, deploying eBPF programs to each node.
• eBPF Programs: Kernel-level programs that observe and enforce security policies.
• Policy Engine: Evaluates security policies and triggers enforcement actions.
• Event Export: Sends security events to external systems for analysis.

Getting Started

Install Tetragon:

helm repo add cilium https://helm.cilium.io/
helm install tetragon cilium/tetragon -n kube-system

Deploy a security policy:

apiVersion: cilium.io/v1alpha1
kind: TracingPolicy
metadata:
  name: "file-monitoring"
spec:
  kprobes:
  - call: "fd_install"
    syscall: false
    args:
    - index: 0
      type: "int"
    - index: 1
      type: "file"
    selectors:
    - matchBinaries:
      - operator: "In"
        values:
        - "/usr/bin/cat"
        - "/usr/bin/less"

Key Features

1. Real-Time Threat Detection: Identify security threats as they occur.
2. Policy Enforcement: Block malicious activity using eBPF-based policies.
3. Process Visibility: Complete visibility into process execution and system calls.
4. Network Security: Monitor and enforce network security policies.
5. Kubernetes Integration: Native integration with Kubernetes pods and namespaces.

Use Cases

• Runtime Security: Detect and prevent malicious activity in running containers.
• Compliance: Monitor system activity for compliance with security policies.
• Forensics: Investigate security incidents with detailed event logs.
• Threat Hunting: Proactively search for security threats using event data.

Comparison with Alternatives

Security Policies

Tetragon uses TracingPolicy CRDs to define security policies:

apiVersion: cilium.io/v1alpha1
kind: TracingPolicy
metadata:
  name: "block-suspicious-exec"
spec:
  kprobes:
  - call: "execve"
    syscall: true
    selectors:
    - matchBinaries:
      - operator: "In"
        values:
        - "/tmp/*"
      actions:
      - action: "Sigkill"

Operational Considerations

• Performance Impact: eBPF programs are efficient but monitor resource usage.
• Policy Complexity: Complex policies may impact performance; start simple.
• Event Volume: High-traffic clusters generate many events; consider filtering.
• Storage: Security events need storage; integrate with external systems.

Common Patterns

• Binary Execution Monitoring: Track which binaries are executed in containers.
• File Access Control: Monitor and control file access based on policies.
• Network Policy Enforcement: Block unauthorized network connections.
• Privilege Escalation Detection: Identify attempts to gain elevated privileges.

Integration with Security Stack

• SIEM Integration: Export events to SIEM systems for correlation and analysis.
• Alerting: Integrate with alerting systems for real-time threat notifications.
• Compliance Tools: Use Tetragon data for compliance reporting and auditing.
• Forensics: Leverage event data for security incident investigation.

Limitations (0.1)

• Early Software: 0.1 is an initial release; expect API changes and feature additions.
• Kernel Requirements: Requires Linux kernel 5.4+ with eBPF support.
• Policy Learning Curve: Writing effective policies requires eBPF knowledge.
• Event Storage: Events are not persisted by default; need external integration.

Looking Ahead

Tetragon 0.1 established the foundation for:

• Advanced Policies: More sophisticated policy capabilities and enforcement actions.
• Performance Improvements: Continued eBPF optimizations and reduced overhead.
• Integration Enhancements: Better integration with security and observability tools.
• CNCF Contribution: Tetragon would later be contributed to CNCF.

Summary

Tetragon 0.1 proved that security observability and enforcement didn’t have to rely on heavy agents or delayed log analysis. By leveraging eBPF to observe and enforce security policies at the kernel level, it provided real-time threat detection and prevention with minimal performance impact, setting a new standard for runtime security in Kubernetes.