Reconnaissance

Reconnaissance

Domain and web application reconnaissance. Discovers subdomains, open ports, endpoints, APIs, and JavaScript routes to build attack surface inventory.

Phases

Domain Assessment

1. Subdomain Discovery - Passive DNS, certificate transparency, DNS brute-forcing, zone transfers
2. Port Scanning - nmap/masscan (top 1000/10000/all), service detection, OS fingerprinting
3. Service Enumeration - Version detection, banner grabbing, protocol-specific enumeration

Web Application Mapping

1. Software Inventory - Dependencies, frameworks, SBOM generation
2. Active Scanning - ffuf, gobuster, nikto, ZAP spider for directories/files
3. API Discovery - REST, GraphQL, SOAP, WebSocket, Swagger/OpenAPI docs
4. JavaScript & SPA - Client-side routes, dynamic scripts, browser storage
5. Surface Analysis - Categorize attack surfaces, prioritize by risk

Output

inventory/  - JSON: subdomains, ports, endpoints, APIs, SBOM
analysis/   - MD: attack-surface, testing-checklist
raw/        - Tool outputs (nmap, ffuf, ZAP, subfinder)

Tools

subfinder, amass, certspotter, crt.sh, nmap, masscan, nuclei, sslscan, ffuf, gobuster, nikto, ZAP, Playwright MCP

Related Skills

• /osint - Run alongside reconnaissance for repository enumeration, secret scanning, and git history analysis

Rules

1. Passive discovery before active scanning
2. Always run /osint in parallel during Phase 2
3. Respect rate limits
4. Verify subdomains are live before port scanning
5. Save all raw tool outputs
6. HTTP response header vhost leaks: Always check response headers on the raw IP (curl -sI http://IP/). Headers like X-Backend-Server, X-Forwarded-Host, X-Served-By, X-Upstream often leak internal hostnames/vhosts not discoverable via DNS or brute-force. Add discovered hostnames to /etc/hosts immediately.
7. Wildcard SSL certs (*.domain.tld in SAN) = strong indicator of hidden vhosts. Always run vhost brute-force with ffuf -u https://IP -k -H "Host: FUZZ.domain.tld" -w subdomains.txt -mc all -fs when wildcard SAN detected. Compare response size/status vs default vhost to identify valid subdomains.
8. VHost enumeration without ffuf: When ffuf/gobuster unavailable, use shell loop: for sub in admin dev api portal dashboard staging git; do code=$(curl -s -o /dev/null -w "%{http_code}:%{size_download}" -H "Host: ${sub}.DOMAIN" http://IP); echo "$sub: $code"; done — filter by response size difference from default page.
9. Web management panels: When discovering admin vhosts (admin., panel., manage.*), check for known management UIs: Nginx UI (manifest.json → "Nginx UI"), Cockpit, Webmin, phpMyAdmin. These often have unauthenticated API endpoints or known CVEs. Check /api/backup, /api/settings, /api/install for Nginx UI specifically.
10. Mobile / native client downloads on the marketing tier: when the public web tier has a download link to an .apk / .dmg / .exe / .ipa, the "real" API endpoint and its required headers are usually only reachable from that client. The web HTML shows nothing useful; the API is gated behind a static User-Agent / Host that's hard-coded in the binary. Always pull the client and decompile/extract before assuming the box is a static-page only. For Android React Native: unzip .apk -d ext/ && file ext/assets/index.android.bundle. The bundle is typically obfuscator.io-style (function _0xNNNN(idx) decoder + array.shift() IIFE that loops until a parseInt-equation == target). Don't reverse it by hand — extract decoder + array literal + IIFE into a standalone Node.js file and dump every index in seconds: for(let i=baseHex; i<baseHex+arr.length; i++) console.log(i.toString(16), _0xDecode(i));. Then reconstruct the obfuscated object literal of the API call (URL = concatenation of 4–7 short fragments, headers likewise) and replay with the recovered values verbatim.
11. Focused AD port scan for Windows targets: when initial fingerprinting shows a Windows DC archetype (any of 53/135/139/445/389 open), skip -p- and run a focused scan over the 13 AD-relevant ports first — it finishes in seconds and covers everything that matters.

``bash nmap -Pn -sC -sV -p 53,88,135,139,389,445,464,593,636,3268,3269,5985,5986,9389 -oA recon/ad-focused TARGET ` Ports rationale: 53 DNS, 88 Kerberos, 135 RPC, 139/445 SMB, 389/636 LDAP/LDAPS, 464 kpasswd, 593 RPC-over-HTTPS, 3268/3269 GC/GC-LDAPS, 5985 WinRM (HTTP), 5986 WinRM (HTTPS — cert auth), 9389 AD Web Services. Always probe BOTH 5985 and 5986 — when 5985 is filtered, 5986 with client-cert auth is a common foothold path (see skills/system/reference/foothold-patterns.md WinRM cert-auth foothold). Only fall back to -p-` if (a) no flag-yielding service surfaces in the focused scan, or (b) you suspect a non-standard app on a high port (custom web service, RDP-on-non-3389, etc.). Don't burn 30 minutes on full TCP sweeps when the AD archetype is obvious.

1. CT-log enumeration is MANDATORY: CT-log enumeration (crt.sh / certspotter / subfinder) is MANDATORY on every engagement that names an apex domain, INCLUDING grey-box engagements where hostnames were provided — provided hostnames are a seed, not the surface. CDN/WAF-fronted targets additionally get an origin-discovery pass (direct cloud endpoints, archive.org CDX, historical DNS). The crt.sh/subfinder commands already ship in reference/scenarios/subdomain-enumeration.md — use them.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: transilienceai
• Source: transilienceai/communitytools
• License: MIT
• Homepage: https://www.transilience.ai/

Install and usage instructions live in the source repository linked above.