About

Imported from kaviyarasu2007/Master_ (skills/hunting-for-cobalt-strike-beacons/SKILL.md). Install upstream with npx skills add kaviyarasu2007/Master_ --skill hunting-for-cobalt-strike-beacons. Copyright stays with the author (Apache-2.0).

Hunting for Cobalt Strike Beacons

Name: hunting-for-cobalt-strike-beacons
Author: kaviyarasu2007

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.

Use it

Copy one of these into your project. Installing also returns the manifest and these snippets.

yaml

targets:
  - https://api.opensmartroute.ai/api/v1/registry/kaviyarasu2007-master-hunting-for-cobalt-strike-beacons/manifest   # or paste the manifest below

Manifest

An Open Capability Manifest: the router reads it to know what this does, what it costs and when to pick it.

kaviyarasu2007-master-hunting-for-cobalt-strike-beacons.ocm.jsonjson

{
  "ocm": "1",
  "id": "kaviyarasu2007-master-hunting-for-cobalt-strike-beacons",
  "kind": "skill",
  "name": "hunting-for-cobalt-strike-beacons",
  "description": "Detect Cobalt Strike beacon network activity using default TLS certificate signatures (serial 8BB00EE), JA3/JA3S/JARM fingerprints, HTTP C2 profile pattern matching, beacon jitter analysis, and named pipe detection via Zeek, Suricata, and Python PCAP analysis.",
  "publisher": "kaviyarasu2007",
  "version": "1.0.0",
  "capabilities": {
    "domains": [
      "coding",
      "math"
    ],
    "tags": [
      "skill-md",
      "cobalt-strike",
      "beacon",
      "threat-hunting",
      "c2",
      "zeek",
      "suricata",
      "ja3",
      "jarm",
      "network-forensics"
    ],
    "languages": [
      "en"
    ]
  },
  "quality_prior": 0.6,
  "examples": [
    "Detect Cobalt Strike beacon network activity using default TLS certificate signatures (serial 8BB00EE), JA3/JA3S/JARM fingerprints, HTTP C2 profile pattern matching, beacon jitter analysis, and named pipe detection via Zeek, Suricata, and Python PCAP analysis."
  ],
  "primary": false,
  "metadata": {
    "source": {
      "provider": "github",
      "repository": "https://github.com/kaviyarasu2007/Master_",
      "path": "skills/hunting-for-cobalt-strike-beacons/SKILL.md",
      "ref": "1fa95dc9a9ac5965a48c8e58500745134dbf9877",
      "url": "https://github.com/kaviyarasu2007/Master_/blob/1fa95dc9a9ac5965a48c8e58500745134dbf9877/skills/hunting-for-cobalt-strike-beacons/SKILL.md",
      "key": "kaviyarasu2007/Master_/skills/hunting-for-cobalt-strike-beacons/SKILL.md"
    },
    "license": "Apache-2.0"
  },
  "instructions": "# Hunting for Cobalt Strike Beacons\n\n## Overview\n\nCobalt 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",
  "cost": {
    "context_tokens": 543
  }
}

Fetch it by URL: GET /api/v1/registry/kaviyarasu2007-master-hunting-for-cobalt-strike-beacons/manifest?version=1.0.0

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