# hunting-for-cobalt-strike-beacons

> Detect Cobalt Strike beacon network activity using TLS certificate signatures, JA3/JA3S/JARM fingerprints, HTTP C2 profile matching, beacon jitter analysis, and named pipe detection via Zeek, Suricata, and Python PCAP analysis.

- Skill: `mukul975/hunting-for-cobalt-strike-beacons` (Agent Skill, multi-file: 4 files)
- Install (CLI): `npx skillmds add mukul975/hunting-for-cobalt-strike-beacons`
- Raw SKILL.md: https://api.skillmd.com/api/skills/mukul975/hunting-for-cobalt-strike-beacons/raw
- Safety review: PASS (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Security, Coding & Dev Tools, Data & Analytics, Data Analysis, Vulnerability Scanning
- Tags: Beacon Detection, Cobalt Strike, Ja3, Pcap Analysis, Suricata, Threat Hunting, Tls Fingerprinting, Zeek
- License: Apache-2.0
- Author: mukul975 (https://skillmd.com/u/mukul975)
- Updated: 2026-07-06
- Page: https://skillmd.com/skills/mukul975/hunting-for-cobalt-strike-beacons

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# Hunting for Cobalt Strike Beacons

## Overview

Cobalt Strike is the most prevalent command-and-control framework used by both red teams and threat actors. Beacon, its primary payload, communicates with team servers using configurable HTTP/HTTPS/DNS profiles that can mimic legitimate traffic. However, default configurations and behavioral patterns remain detectable through TLS certificate analysis (default serial 8BB00EE), JA3/JA3S fingerprinting, beacon interval jitter analysis, and HTTP malleable profile pattern matching. This skill covers building detection capabilities using Zeek network logs, Suricata IDS rules, and Python-based PCAP analysis to identify beacon callbacks in network traffic.


## When to Use

- When investigating security incidents that require hunting for cobalt strike beacons
- 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

## Prerequisites

- Zeek 6.0+ with JA3 and HASSH packages installed
- Suricata 7.0+ with Emerging Threats ruleset
- Python 3.9+ with scapy and dpkt libraries
- Network traffic captures (PCAP) or live Zeek logs
- RITA (Real Intelligence Threat Analytics) for beacon scoring
- Threat intelligence feeds with known Cobalt Strike IOCs

## Steps

### Step 1: TLS Certificate Analysis
Detect default Cobalt Strike certificates using JA3S fingerprints, certificate serial numbers, and JARM fingerprints in Zeek ssl.log.

### Step 2: Beacon Interval Analysis
Analyze connection timing patterns to identify regular callback intervals with configurable jitter, characteristic of beacon behavior.

### Step 3: HTTP Profile Detection
Match HTTP request patterns (URI paths, headers, user-agents) against known malleable C2 profiles.

### Step 4: Correlate and Score
Combine multiple indicators (TLS + timing + HTTP profile) into a composite beacon confidence score.

## Expected Output

JSON report containing detected beacon candidates with confidence scores, TLS fingerprints, timing analysis, HTTP profile matches, and recommended response actions.