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recon-and-methodology

yaklang/hack-skills

Systematic reconnaissance and bug-hunting methodology for mapping assets, discovering endpoints, and building structured testing plans.

What is recon-and-methodology?

A comprehensive playbook for bug bounty reconnaissance covering subdomain enumeration, service discovery, technology fingerprinting, endpoint mapping, and vulnerability testing strategy. Use this when starting work on a new target to systematically uncover attack surface and prioritize testing efforts like top hunters do.

  • Subdomain enumeration via passive sources (certificate transparency, APIs) and active DNS brute force
  • Service and port discovery with HTTP probing and technology fingerprinting
  • Endpoint discovery through directory brute force, parameter fuzzing, and JavaScript source mining
  • API endpoint detection including Swagger/OpenAPI and GraphQL discovery
  • Source code reconnaissance including GitHub exposure and environment file discovery
  • Testing methodology framework based on input reflection, encoding, and output observation

How to install recon-and-methodology

npx skills add https://github.com/yaklang/hack-skills --skill recon-and-methodology
Claude Code
Cursor
Windsurf
Cline

How to use recon-and-methodology

  1. 1.Define scope and target selection for your engagement
  2. 2.Run subdomain enumeration using passive sources (subfinder, crt.sh) then active DNS brute force (massdns, ffuf)
  3. 3.Resolve discovered subdomains and probe for live HTTP services using httpx
  4. 4.Fingerprint web technologies via headers, cookies, and framework detection
  5. 5.Discover endpoints through directory brute force (ffuf, feroxbuster) and parameter fuzzing (arjun)
  6. 6.Mine JavaScript files and wayback machine for additional endpoints and API paths
  7. 7.Check for exposed files (.env, .git/config, wp-config.php) and GitHub repository leaks
  8. 8.Run Nuclei templates against discovered assets to identify common misconfigurations

Use cases

Good for
  • Map all in-scope assets for a new bug bounty target before vulnerability testing
  • Discover hidden subdomains and endpoints that competitors may have missed
  • Identify technology stack and common misconfigurations (CORS, S3 buckets, exposed files)
  • Find API endpoints and parameters through JavaScript mining and directory brute force
  • Systematically test authentication, file upload, and admin features for high-severity bugs
Who it's for
  • Bug bounty hunters and security researchers
  • Penetration testers conducting authorized assessments
  • Security engineers building reconnaissance automation
  • Teams performing application security testing

recon-and-methodology FAQ

What's the difference between passive and active subdomain enumeration?

Passive enumeration (certificate transparency, APIs, SecurityTrails) requires no DNS queries to the target and leaves no logs. Active enumeration (DNS brute force with massdns/ffuf) sends queries directly to the target's DNS servers and may be detected. Use passive first, then active if scope permits.

How do I discover API endpoints if they're not in JavaScript or directories?

Check common API paths (/swagger.json, /api-docs, /openapi.json, /graphql), use parameter discovery tools like arjun and x8, mine JavaScript files with LinkFinder and gau, check wayback machine URLs, and test for virtual host discovery which may expose separate API subdomains.

What should I prioritize when testing a new target?

Follow the priority sequence: authentication and password reset (account takeover), file upload and profile edit (stored XSS, IDOR), admin panels (BFLA), payment flows (business logic), and import/export features (XXE, SSTI). Test each input for reflection, encoding bypass, and output location.

How do I find exposed credentials and secrets?

Use trufflehog and gitleaks to scan GitHub repositories for secrets in commit history. Search GitHub with dorks like 'site:github.com "target.com" api_key' or 'org:target-org secret'. Check common paths like /.env, /.git/config, /config.json, /wp-config.php, and /backup files.

What are quick wins to look for in reconnaissance?

Check for CORS misconfiguration (Access-Control-Allow-Origin: * with credentials), publicly accessible S3 buckets, exposed .env and configuration files, unprotected admin panels, and common CVEs via Nuclei templates. These often yield quick P2/P3 findings.

Full instructions (SKILL.md)

Source of truth, from yaklang/hack-skills.


name: recon-and-methodology description: >- Reconnaissance and methodology playbook. Use when mapping assets, discovering endpoints, fingerprinting technology, and building a structured testing plan for a new target.

SKILL: Recon and Methodology — Expert Bug Bounty Playbook

AI LOAD INSTRUCTION: Systematic recon and bug-finding methodology from top bug hunters. Covers subdomain enumeration, endpoint discovery, tech fingerprinting, and the hunter's mental model for finding bugs that others miss. Key insight: most high-severity bugs are found through systematic coverage, not just clever payloads.


1. RECON HIERARCHY

Target Selection
└── Scope Definition (in-scope assets)
    └── Asset Discovery (subdomains, IPs, domains)
        └── Tech Fingerprinting (what's running)
            └── Endpoint Discovery (attack surface)
                └── Vulnerability Testing (per vulnerability type)

2. SUBDOMAIN ENUMERATION (CRITICAL FIRST STEP)

Passive (no DNS queries to target)

# Subfinder (aggregates multiple sources):
subfinder -d target.com -o subdomains.txt

# Amass passive:
amass enum -passive -d target.com

# Certsh (certificate transparency):
curl -s "https://crt.sh/?q=%.target.com&output=json" | jq -r '.[].name_value' | sort -u

# SecurityTrails API, Shodan:
# Web: https://securitytrails.com/list/apex_domain/target.com

Active (DNS brute force + resolution)

# Massdns + wordlist:
massdns -r /path/to/resolvers.txt -t A -o S -w output.txt \
  <(cat wordlist.txt | sed 's/$/.target.com/')

# ffuf for subdomain brute:
ffuf -w subdomains-wordlist.txt -u https://FUZZ.target.com \
  -mc 200,301,302,403 -H "Host: FUZZ.target.com"

# DNSx for bulk resolution:
cat subdomains.txt | dnsx -a -resp -o resolved.txt

# Recommended wordlist: SecLists/Discovery/DNS/

Virtual Host Discovery

# ffuf vhost mode:
ffuf -w wordlist.txt -u https://target.com \
  -H "Host: FUZZ.target.com" -mc 200,301,403

# gobuster vhost:
gobuster vhost -u https://target.com -w wordlist.txt

3. SERVICE AND PORT DISCOVERY

# Fast port scan (common ports):
nmap -T4 -F target.com -oN ports.txt

# Comprehensive scan on resolved subdomains:
cat resolved_ips.txt | nmap -iL - --open -p 80,443,8080,8443,8888,3000,5000 -oG scan.txt

# httpx for HTTP probing:
cat subdomains.txt | httpx -title -tech-detect -status-code -o live_hosts.txt

# masscan for speed on large IP ranges:
masscan -p 80,443,8080,8443 10.0.0.0/8 --rate=1000

4. WEB TECHNOLOGY FINGERPRINTING

# Wappalyzer (browser extension) or:
whatweb https://target.com

# httpx with tech detection:
httpx -u https://target.com -tech-detect

# Check headers manually:
curl -sI https://target.com | grep -i "server\|x-powered-by\|x-generator\|cf-ray"

# Fingerprint from:
- Server header: nginx/1.18, Apache/2.4, IIS/10.0
- X-Powered-By: PHP/7.4, ASP.NET
- Cookies: PHPSESSID (PHP), JSESSIONID (Java), _rails_session (Rails)
- HTML comments: <!-- Drupal 9 -->
- Meta generator: <meta name="generator" content="WordPress 6.2">
- JS framework files: /static/js/angular.min.js

5. ENDPOINT DISCOVERY

Directory Brute Force

# ffuf (fastest):
ffuf -u https://target.com/FUZZ -w /usr/share/seclists/Discovery/Web-Content/raft-medium-files.txt \
  -mc 200,301,302,403 -t 50 -o dirs.txt

# Gobuster:
gobuster dir -u https://target.com -w wordlist.txt -x php,html,js,json

# feroxbuster (recursive):
feroxbuster -u https://target.com -w wordlist.txt -x php,html,txt -r

Parameter Discovery

# Arjun (hidden parameter finder):
arjun -u https://target.com/api/endpoint

# x8:
x8 -u https://target.com/api/endpoint -w params-wordlist.txt

JavaScript Source Mining

# Extract endpoints from JS files:
gau target.com | grep '\.js$' | httpx -mc 200 | xargs -I{} curl -s {} | \
  grep -oE '"/[a-zA-Z0-9/_-]+"' | sort -u

# LinkFinder:
python3 linkfinder.py -i https://target.com -d -o output.html

# GetAllURLs (gau):
gau target.com | sort -u > all_urls.txt

# Wayback URLs:
waybackurls target.com | sort -u > wayback_urls.txt

API Endpoint Discovery

# Common API paths:
ffuf -u https://target.com/FUZZ -w /SecLists/Discovery/Web-Content/api/api-endpoints.txt

# Swagger/OpenAPI:
test: /swagger.json /api-docs /openapi.json /v2/api-docs /.well-known/ /docs/

# GraphQL:
test: /graphql /gql /v1/graphql /api/graphql

6. SOURCE CODE RECON

GitHub / GitLab Exposure

# trufflehog (secret scanner in git history):
trufflehog git https://github.com/target-org/target-repo

# gitleaks:
gitleaks detect --source /path/to/cloned/repo

# Manual GitHub search:
# site:github.com "target.com" "api_key" OR "secret" OR "password"
# site:github.com "target.com" ".env" OR "config.php" OR "db_password"

# GitHub dorks:
# "target.com" extension:env
# "target.com" filename:*.config password
# org:target-org secret OR password OR apikey

Exposed Environment Files

# Check common paths:
https://target.com/.env
https://target.com/.git/config
https://target.com/config.json
https://target.com/config.yaml
https://target.com/credentials.json
https://target.com/secrets.json
https://target.com/wp-config.php
https://target.com/backup.sql
https://target.com/backup.zip

7. ZSEANO'S TESTING METHODOLOGY

Core Philosophy

  1. Go deep on one program rather than spread across many — learn the application thoroughly
  2. Build a profile of the company — tech stack, developers, processes
  3. Look where others don't — check error pages, admin paths, old versions, mobile API
  4. Follow the filter — if input is filtered somewhere, that functionality exists and may be bypassed

Testing Sequence (One Page / Feature)

For each input point:
1. Non-malicious HTML tags (<h2>, <img>) → are they reflected?
2. Incomplete tags → what happens? (<iframe src=//evil.com )
3. Encoding tests → %0d, %0a, %09, <%00
4. Observe the OUTPUT too (not just response) — where does your input appear?
5. Test same input in ALL similarly-structured pages (shared code → shared vuln)
6. Check if the same parameter exists in mobile/API endpoint (less protected)

Parameter Insights

- Each parameter tells a story: "what does this do server-side?"
- Filename → OS interaction → Path Traversal / CMDi
- URL/location → HTTP fetch → SSRF
- Template/HTML parameter → render function → SSTI
- XML field → parser → XXE
- SQL filter → query → SQLi
- User-content → storage → Stored XSS

8. BUG BOUNTY PROGRAM TRIAGE (WHERE TO SPEND TIME)

High-Value Target Selection

✓ Programs with large scope (*.target.com)
✓ Programs that pay for P2/P3 (not just RCE)
✓ Programs with recent tech changes (migrations = new bugs)
✓ Programs with active development (new features = new attack surface)
× Avoid: frozen/old codebases with well-known CVEs (already claimed)
× Avoid: strict programs with narrow scope (less surface)

High-Value Feature Focus (by bug probability)

Priority 1: Authentication, password reset, 2FA → account takeover
Priority 2: File upload, profile edit, API endpoints → stored XSS, IDOR
Priority 3: Admin panels, user management → BFLA, privilege escalation
Priority 4: Payment flows, subscription → business logic
Priority 5: Import/export, template rendering → XXE, SSTI

9. NUCLEI TEMPLATES (AUTOMATED SCANNING)

# Run all on target:
nuclei -u https://target.com -t /nuclei-templates/ -o nuclei-results.txt

# Specific categories:
nuclei -u https://target.com -t cves/ -severity critical,high
nuclei -u https://target.com -t exposures/
nuclei -u https://target.com -t misconfiguration/

# On subdomain list:
cat subdomains.txt | nuclei -t exposures/ -t misconfiguration/ -o exposed.txt

10. COMMON MISCONFIGURATIONS (QUICK WINS)

□ CORS: Access-Control-Allow-Origin: * with credentials → CSRF + data theft
□ S3 bucket public: curl https://target.s3.amazonaws.com/
□ Directory listing: response contains "Index of /"
□ .git exposed: curl https://target.com/.git/config
□ .env exposed: curl https://target.com/.env
□ Debug mode: stack traces in production (source code exposure)
□ Default credentials: admin:admin, admin:password on admin panels
□ phpinfo.php: curl https://target.com/phpinfo.php
□ Backup files: config.bak, database.sql.gz, app.zip
□ GraphQL introspection enabled: POST /graphql {"query":"{__schema{types{name}}}"}
□ Admin panels: /admin /manager /console /phpmyadmin /wp-admin

11. QUICK REFERENCE TOOLS

CategoryTool
Subdomain enumsubfinder, amass, massdns
Port scannmap, masscan
HTTP probehttpx
Dir bruteffuf, feroxbuster, gobuster
JS miningLinkFinder, gau, waybackurls
Secret scantrufflehog, gitleaks
Parameter fuzzarjun, x8
Vuln scannuclei
Proxy/interceptBurp Suite Pro
JWT attacksjwt_tool
SQLisqlmap
XSSdalfox, XSStrike
SSRFSSRFmap, Gopherus

12. JAVA MIDDLEWARE FINGERPRINT MATRIX

MiddlewareDetection PathKey Indicators
Apache Tomcat/manager/html, /manager/statusDefault creds: tomcat:tomcat, admin:admin
JBoss / WildFly/jmx-console/, /web-console/JMX MBean access, WAR deployment
WebLogic/console/, /wls-wsat/T3 protocol on 7001/7002, IIOP
Spring Boot Actuator/actuator/, /actuator/env, /actuator/heapdumpJSON endpoint listing, heap dump contains secrets
Spring Boot (alt paths)/actuator/jolokia, /actuator/gateway/routesJolokia JMX bridge, Gateway route injection
Jenkins/script, /manageGroovy console, API token in cookie
GlassFish/common/, /theme/Admin on 4848, default empty password
Jetty/jolokia/JMX access
Resin/resin-admin/Admin panel

Spring Boot Actuator Exploitation Priority

/actuator/env          → Leak environment variables (DB creds, API keys)
/actuator/heapdump     → Download JVM heap → search for passwords in memory
/actuator/jolokia      → JMX → possible RCE via MBean manipulation
/actuator/gateway/routes → Spring Cloud Gateway → SpEL injection (CVE-2022-22947)
/actuator/configprops  → All configuration properties
/actuator/mappings     → All URL mappings (hidden endpoints)
/actuator/beans        → All Spring beans
/actuator/threaddump   → Thread dump (may leak session tokens / secrets in stack frames)

13. INFORMATION LEAK DETECTION CHECKLIST

Version Control & Backup Leaks

/.git/HEAD                    → Git repository exposed
/.svn/entries                 → SVN metadata
/.svn/wc.db                   → SVN SQLite database
/.hg/requires                 → Mercurial
/.bzr/README                  → Bazaar
/.DS_Store                    → macOS directory listing

Backup File Patterns

/backup.zip    /backup.tar.gz    /backup.sql
/wwwroot.rar   /www.zip          /web.zip
/db.sql        /database.sql     /dump.sql
/config.php.bak    /config.php~    /config.php.swp
/.config.php.swp   /wp-config.php.bak
/.env          /.env.bak         /.env.production

API Documentation & Debug

/swagger-ui.html              → Swagger/OpenAPI
/swagger-ui/                  → Swagger UI
/api-docs                     → API documentation
/graphql                      → GraphQL playground
/graphiql                     → GraphQL IDE
/debug/                       → Debug endpoints
/phpinfo.php                  → PHP configuration
/server-status                → Apache status
/server-info                  → Apache info
/nginx_status                 → Nginx status

Cloud & Infrastructure

/.aws/credentials             → AWS credentials
/.docker/config.json          → Docker registry auth
/robots.txt                   → Disallowed paths (hint list)
/sitemap.xml                  → Full URL listing
/crossdomain.xml              → Flash cross-domain policy
/.well-known/                 → Various well-known URIs