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Anthropic-Cybersecurity-Skills/skills/hunting-for-cobalt-strike-beacons/SKILL.md
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mukul975 efca3ec611 feat: add NIST CSF 2.0 nist_csf field to all 754 cybersecurity skills
Mapped every skill to NIST CSF 2.0 subcategory IDs (GV/ID/PR/DE/RS/RC functions)
based on subdomain and content analysis. Restores 11 skills corrupted during
prior rebase, re-enriching with ATLAS, D3FEND, NIST AI RMF, and CSF 2.0 fields.

All 754 skills now carry structured mappings for all 5 security frameworks:
- MITRE ATT&CK (in tags)
- MITRE ATLAS v5.5 (atlas_techniques)
- MITRE D3FEND v1.3 (d3fend_techniques)
- NIST AI RMF 1.0 (nist_ai_rmf)
- NIST CSF 2.0 (nist_csf)
2026-04-06 11:17:40 +02:00

2.7 KiB

name, description, domain, subdomain, tags, version, author, license, nist_csf
name description domain subdomain tags version author license nist_csf
hunting-for-cobalt-strike-beacons 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. cybersecurity threat-hunting
cobalt-strike
beacon
threat-hunting
c2
zeek
suricata
ja3
jarm
network-forensics
1.0 mahipal Apache-2.0
DE.CM-01
DE.AE-02
DE.AE-07
ID.RA-05

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.