hunting-for-cobalt-strike-beacons

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. Use when detecting cobalt strike beacon network activity using default tls certificate.
domain	cybersecurity
subdomain	threat-hunting
tags	["cobalt-strike","beacon","threat-hunting","c2","zeek","suricata","ja3","jarm","network-forensics"]
version	1.0
author	oyi77
license	Apache-2.0
nist_csf	["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

Trigger phrases:

• "hunting for cobalt strike beacons"

• "Detect Cobalt Strike beacon network activity using default TLS certificate signa"

• 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

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

• 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

# 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() -> :
     {k: re.findall(v, text)  k, v  IOC_PATTERNS.items()}