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

12. JAVA MIDDLEWARE FINGERPRINT MATRIX

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/shutdown     → POST to shutdown application (DoS)

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