01 recon osint

Reconnaissance & OSINT Automation

Purpose

Enable Claude to conduct comprehensive reconnaissance and open-source intelligence gathering during authorized security assessments. Claude performs passive and active recon using its native analysis capabilities and orchestrates the included scripts for automation at scale.

Authorization Required: Always confirm written authorization for the target scope before proceeding. Unauthorized reconnaissance is illegal in most jurisdictions.

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Activation Triggers

This skill activates when the user asks about:

• Subdomain enumeration or discovery
• DNS reconnaissance, zone transfers, or DNS record analysis
• OSINT gathering on a domain, organization, or person
• Technology fingerprinting or stack identification
• Port scanning, service detection, or banner grabbing
• Google dorking or advanced search query generation
• WHOIS, certificate transparency, or Shodan queries
• Attack surface mapping or perimeter discovery

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Prerequisites

pip install requests dnspython python-whois beautifulsoup4 shodan

Optional enhanced capabilities:

• nmap — Active port scanning
• amass — Advanced subdomain enumeration
• theHarvester — Email and domain harvesting
• Shodan API key — Internet-wide device search
• Censys API key — Certificate and host search

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Core Capabilities

1. Passive Reconnaissance (No Direct Target Contact)

When the user asks for passive recon or OSINT:

1. WHOIS Analysis — Query domain registration records for registrant, registrar, nameservers, and dates. Flag privacy-protected registrations and registrar patterns.
2. Certificate Transparency Logs — Search crt.sh for all certificates issued to the domain and subdomains. Extract SANs (Subject Alternative Names) to discover hidden subdomains.
3. DNS Records (Passive) — Enumerate A, AAAA, MX, NS, TXT, SOA, SRV, and CNAME records using public resolvers. Analyze SPF, DKIM, and DMARC for email security posture.
4. Search Engine Dorking — Generate targeted dork queries to discover exposed files, login portals, and configuration leaks:
   • site:target.com filetype:pdf — Exposed documents
   • site:target.com inurl:admin — Admin panels
   • site:target.com ext:env OR ext:config — Config files
   • "@target.com" site:linkedin.com — Employee enumeration
   • "target.com" site:pastebin.com — Credential leaks
5. Shodan/Censys Queries — Search for internet-exposed services, open ports, banners, and vulnerabilities associated with the target's IP ranges.
6. Git/Code Repository Search — Search GitHub/GitLab for leaked credentials, API keys, and internal information:
   • org:targetorg api_key
   • filename:.env target.com
   • "target.com" password

2. Subdomain Enumeration

When the user asks to enumerate subdomains:

1. Certificate Transparency — Extract all SANs from crt.sh/Censys certificates (most effective passive method)
2. DNS Brute-Force — Run subdomain_enum.py against the common wordlist in resources/
3. Wildcard Detection — Query random subdomains to detect wildcard DNS responses and filter false positives
4. Resolution Validation — Resolve all candidates to IP addresses; discard NXDOMAINs
5. HTTP Probing — Check which subdomains respond on ports 80/443; identify web applications
6. Infrastructure Grouping — Group discovered subdomains by IP/ASN to map cloud vs. on-prem assets

Output format for subdomain findings:

Target: example.com
Discovery Method: CT Logs + DNS Brute-Force
Discovered: 47 subdomains

LIVE SUBDOMAINS:
  admin.example.com       → 203.0.113.10  [HTTP 200] [nginx/1.18]
  dev.example.com         → 203.0.113.11  [HTTP 302 → /login]
  api.example.com         → 203.0.113.12  [HTTP 200] [cloudflare]
  internal.example.com    → 10.0.0.5      [No public response — internal?]

INFRASTRUCTURE CLUSTERS:
  203.0.113.10-15 → AS12345 (Company Hosting)
  Cloudflare CDN → 7 subdomains proxied

3. Active Port Scanning & Service Detection

When the user asks to scan ports or detect services:

1. Define scan scope (host, subnet, CIDR range) and confirm authorization
2. Select scan technique: SYN scan (requires root), connect scan (no root), or stealth options
3. Run top-1000 ports first, then targeted service ports
4. Perform service version detection (-sV) on all open ports
5. Run OS fingerprinting (-O) if authorized
6. Grab banners from discovered services
7. Flag services with known vulnerabilities based on version data

Provide Nmap commands ready to run:

# Quick discovery
nmap -sn 203.0.113.0/24

# Top 1000 TCP ports with service detection
nmap -sV -sC --top-ports 1000 -oA scan_results 203.0.113.10

# Full port scan with script engine
nmap -sV -sC -p- -T4 -oA full_scan 203.0.113.10

4. DNS Reconnaissance

When the user asks for DNS analysis:

1. Enumerate all record types: A, AAAA, MX, NS, TXT, SOA, SRV, CNAME, PTR
2. Zone Transfer Attempt (AXFR) — Try against all discovered nameservers:

   dig AXFR @ns1.example.com example.com
   

3. Email Security Analysis:
   • SPF: Check for ~all (softfail) or ?all (neutral) — both are weak
   • DMARC: Missing DMARC = zero enforcement; p=none = monitoring only
   • DKIM: Check selector existence and key strength
4. Reverse DNS — PTR lookups on all discovered IPs to find additional hostnames
5. DNS History — Check SecurityTrails or PassiveDNS for historical DNS records that may reveal old infrastructure

Flag these misconfigurations:

• Zone transfer allowed → Exposes full DNS zone
• No DMARC record → Email spoofing possible
• SPF +all → Any server can send as this domain
• DNSSEC not configured → DNS cache poisoning risk

5. Technology Fingerprinting

When the user asks to fingerprint technology:

1. Analyze HTTP response headers:
   • Server: → Web server and version
   • X-Powered-By: → Application framework
   • Set-Cookie: names → Session framework (PHPSESSID=PHP, JSESSIONID=Java)
   • X-Generator: / X-WordPress-Cache: → CMS
2. Examine HTML source for meta tags, script includes, CSS frameworks
3. Check /robots.txt, /sitemap.xml, /.well-known/ for framework leaks
4. Test common CMS paths (/wp-admin/, /administrator/, /wp-json/)
5. Analyze JavaScript files for version strings
6. Detect WAF presence through header analysis and response behavior
7. Identify CDN (Cloudflare, Akamai, Fastly, CloudFront) via IP ranges and headers

Technology stack report format:

URL: https://example.com

WEB SERVER:    nginx/1.18.0 (Ubuntu)
APPLICATION:   WordPress 6.4.2
LANGUAGE:      PHP 8.1
DATABASE:      MySQL (inferred from wp-config patterns)
CDN/WAF:       Cloudflare
JS LIBRARIES:  jQuery 3.6.0, Bootstrap 5.3
TLS:           TLS 1.3, ECDHE-RSA-AES256-GCM-SHA384

NOTABLE HEADERS:
  ✗ Missing: X-Content-Type-Options
  ✗ Missing: X-Frame-Options
  ✗ Missing: Content-Security-Policy
  ✓ Present: Strict-Transport-Security

6. OSINT Correlation & Reporting

When the user asks to correlate OSINT findings:

1. Cross-reference IP ranges across WHOIS, ASN lookups, and cloud provider IP lists
2. Map employee data (LinkedIn/email patterns) to organizational structure
3. Correlate exposed credentials from paste sites against discovered email formats
4. Identify third-party services and SaaS platforms in use (via DNS records, JS imports)
5. Build infrastructure map showing relationships between assets

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Output Standards

Every recon engagement should produce a structured report:

# Reconnaissance Report — [Target]
Date: [Date] | Scope: [Authorized Scope] | Analyst: [Name]

## Executive Summary
[2-3 sentence overview of key findings]

## Discovered Assets
- Subdomains: N found, N live
- IP Ranges: [CIDRs]
- Open Services: [Top findings]
- Technologies: [Stack summary]

## Key Findings
1. [High-impact finding with evidence]
2. [Medium-impact finding]
...

## Attack Surface Summary
[Map of entry points for follow-on testing]

## Recommended Next Steps
- Feed live web apps → Skill 09 (Web Security)
- Feed discovered services → Skill 02 (Vulnerability Scanner)
- Feed cloud assets → Skill 10 (Cloud Security)

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Script Reference

subdomain_enum.py

# Passive CT log enumeration
python scripts/subdomain_enum.py --domain target.com --passive-only --output results.json

# Active brute-force with custom wordlist
python scripts/subdomain_enum.py --domain target.com --wordlist resources/common_subdomains.txt --threads 20 --output results.json

dns_recon.py

# Full DNS reconnaissance
python scripts/dns_recon.py --domain target.com --output dns_report.json

# Check zone transfer vulnerability
python scripts/dns_recon.py --domain target.com --check-zone-transfer

tech_fingerprint.py

# Single URL analysis
python scripts/tech_fingerprint.py --url https://target.com --output tech_report.json

# Batch URL fingerprinting
python scripts/tech_fingerprint.py --urls urls.txt --output tech_report.json

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Skill Integration

Next Step	Condition	Target Skill
Vulnerability assessment	Live services discovered	→ Skill 02
Web application testing	Web apps found	→ Skill 09
Cloud asset auditing	Cloud-hosted assets found	→ Skill 10
Network traffic analysis	PCAP capture available	→ Skill 08
IOC correlation	Suspicious infrastructure found	→ Skill 06

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References

• OWASP Testing Guide — Information Gathering
• MITRE ATT&CK — Reconnaissance (TA0043)
• Certificate Transparency — crt.sh
• Shodan Search Engine
• DNSDumpster
• Google Hacking Database (GHDB)

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v3.0 Enhancements (2026 Update)

Sharper, more current recon tradecraft:

• Subdomain takeover detection — for every discovered subdomain with a dangling CNAME (pointing to an unclaimed S3/Azure/GitHub Pages/Heroku/Fastly target), flag it as a takeover candidate and identify the fingerprint of the orphaned service.
• Cloud asset discovery — enumerate public S3/GCS/Azure Blob buckets and storage by permutation of the org name; check for listable/world-readable buckets (use cloud_enum-style logic). Map ASN → CIDR → cloud-provider attribution.
• JA4+ / favicon hashing — pivot on favicon mmh3 hashes and JARM/JA4S server fingerprints in Shodan/Censys to find sibling infrastructure behind CDNs.
• GraphQL & API recon — probe /graphql for introspection; harvest schema, types, and mutations to feed Skill 09.
• Breach & credential intel — correlate discovered email formats against HaveIBeenPwned and public combolists (passive only) to prioritize accounts.
• Source-code & CI leaks — extend dorking to GitHub Actions logs, npm/PyPI package metadata, and *.map source maps that leak internal paths.

Precision rule: always separate confirmed assets (resolved + responding) from candidate assets (CT-log only) in output, and tag the discovery source per asset so findings are reproducible.

Added references

• can-i-take-over-xyz — subdomain takeover fingerprints
• JA4+ network fingerprinting