Detecting Beaconing Patterns With Zeek

---
name: detecting-beaconing-patterns-with-zeek
description: 'Use when performs statistical analysis of Zeek conn.log connection intervals
  to detect C2 beaconing patterns. Uses the ZAT library to load Zeek logs into Pandas
  DataFrames, calculates inter-arrival time standard deviation, and flags periodic
  connections with low jitter. Use when hunting for command-and-control callbacks
  in network data.

  '
domain: cybersecurity
tags:
- detecting
- beaconing
- patterns
- with
subdomain: security-operations
version: '1.0'
author: oyi77
license: Apache-2.0
nist_csf:
- DE.CM-01
- RS.MA-01
- GV.OV-01
- DE.AE-02
category: cybersecurity
---

# Detecting Beaconing Patterns With Zeek

## Overview

Cybersecurity skill for detecting beaconing patterns with zeek. Follows industry best practices and security standards.

## When to Use

**Trigger phrases:**
- "detecting beaconing patterns with zeek"
- "When investigating security incidents that require detecting beaconing patterns"
- "When building detection rules or threat hunting queries for this domain"
- "When SOC analysts need structured procedures for this analysis type"


- When investigating security incidents that require detecting beaconing patterns with zeek
- When building detection rules or threat hunting queries for this domain
- When SOC analysts need structured procedures for this analysis type
- When validating security monitoring coverage for related attack techniques


## When NOT to Use

- When you lack proper authorization for testing
- For production systems without change management
- When the task requires legal or compliance expertise beyond technical scope


## Prerequisites

- Familiarity with security operations concepts and tools
- Access to a test or lab environment for safe execution
- Python 3.8+ with required dependencies installed
- Appropriate authorization for any testing activities

## Workflow

```python
# Example: IOC detection
import re

IOC_PATTERNS = {
    "ip": r"\b(?:\d{1,3}\.){3}\d{1,3}\b",
    "domain": r"\b[a-z0-9-]+\.[a-z]{2,}\b",
    "hash_md5": r"\b[a-f0-9]{32}\b",
    "hash_sha256": r"\b[a-f0-9]{64}\b",
}

def extract_iocs(text: str) -> dict:
    return {k: re.findall(v, text) for k, v in IOC_PATTERNS.items()}
```

1. **Define Detection Scope** — Identify the specific beaconing patterns techniques or indicators to hunt. Map to MITRE ATT&CK tactics/techniques where applicable.
2. **Collect Baseline Data** — Gather historical logs and establish normal behavior patterns for beaconing patterns.
3. **Build Detection Queries** — Write zeek queries targeting beaconing patterns indicators. Use platform-specific query language for optimal performance.
4. **Execute Hunts** — Run queries against the collected data, starting with broad filters and narrowing down.
5. **Triage Results** — Investigate alerts, filter false positives, and validate findings against known-good behavior.
6. **Document Findings** — Record confirmed detections, IOCs, and affected systems. Update detection rules based on findings.

## Tools

- **zeek** — Primary tool for this skill
- **SIEM Platform** — Central log aggregation and query execution
- **Sigma Rules** — Vendor-agnostic detection rule format
- **MITRE ATT&CK Navigator** — Technique mapping and coverage analysis


## Process

1. **Reconnaissance** — Gather target information, identify attack surface, enumerate services
1. **Analysis/Exploitation** — Execute the technique, analyze results, document findings
1. **Reporting** — Document IOCs, write findings, provide remediation recommendations

## Verification

- [ ] All beaconing patterns procedures executed completely and documented
- [ ] Findings validated against multiple data sources
- [ ] False positives identified and filtered
- [ ] Results documented with evidence and timestamps
- [ ] Recommendations provided with risk-based prioritization

## Anti-Rationalization Table

| Rationalization | Reality |
|---|---|
| "We are too small to be targeted" | Automated attacks target everyone. Size does not matter. |
| "Security slows us down" | A breach slows you down 100x more. Build security in from the start. |
| "We will fix it after launch" | Vulnerabilities in production are exploited within hours. Fix before deploy. |