Practical Bug Bounty: A Complete Guide to Finding & Reporting Vulnerabilities
Introduction
Bug bounty hunting has become one of the most exciting and rewarding fields in cybersecurity. Ethical hackers and security researchers worldwide participate in bug bounty programs to identify vulnerabilities in applications, report them to organizations, and earn rewards.
But what separates an average bug bounty hunter from a highly successful one?
- Deep technical knowledge of vulnerabilities
- Understanding of OWASP Top 10 & beyond
- Effective reconnaissance & testing techniques
- Crafting professional-quality reports
This guide will provide a practical, step-by-step approach to conducting bug bounty hunting, covering OWASP Top 10 vulnerabilities, real-world exploitation techniques, and how to write an impactful report.
Setting Up Your Bug Bounty Hunting Environment
Before you start hacking, you need the right tools. Here's a basic setup:
🔹 Essential Tools & Platforms
- Bug Bounty Platforms: HackerOne, Bugcrowd, Intigriti, YesWeHack
- Reconnaissance Tools: Amass, Subfinder, Assetfinder
- Scanning Tools: Nmap, Shodan, Dirbuster, FFUF
- Exploitation Tools: Burp Suite, SQLmap, XSStrike
- API Testing: Postman, Hoppscotch
- Browser Extensions: Wappalyzer,
- HackTools, Cookie-Editor
🖥️ Setting Up Your Lab
1. Install Kali Linux or Parrot OS – Preloaded with security tools
2. Use Virtual Machines or Cloud Services – Try Hack The Box, TryHackMe
3. Sign Up for Public Bug Bounty Programs – Choose beginner-friendly programs
Understanding the OWASP Top 10 & Exploiting Vulnerabilities
The OWASP Top 10 is the most critical web application vulnerabilities list. Let’s go through each with real-world examples, testing methods, and mitigation techniques.
🔴 1. Broken Access Control
❌ Issue: Attackers access restricted areas or modify other users' data.
🛠️ Exploitation:
Test IDOR (Insecure Direct Object References)
GET /user/transactions?user_id=123Changing user_id=123 to user_id=124 may leak another user’s data.
Test Admin Panel Access
Try accessing /admin or /dashboard directly.
✅ Fix: Implement role-based access control (RBAC).
🟠 2. Cryptographic Failures
❌ Issue: Weak encryption allows password theft and session hijacking.
🛠️ Exploitation:
Check for HTTP instead of HTTPS
Look for weak hashing (MD5, SHA1)
echo -n "password" | md5sumIf passwords are stored using MD5, they are easy to crack.
✅ Fix: Use bcrypt or Argon2 for password hashing.
🟢 3. Injection Attacks
❌ Issue: Attackers inject malicious SQL, NoSQL, or OS commands.
🛠️ Exploitation:
SQL Injection (Bypass Authentication)
' OR 1=1 --Command Injection
; ls -la✅ Fix: Use prepared statements and input sanitization.
🔵 4. Insecure Design
❌ Issue: Weak security policies allow business logic abuse.
🛠️ Exploitation:
Bypass password reset validation
If a system resets passwords without verifying user identity, attackers can take over accounts.
Exploit weak CAPTCHA implementations
✅ Fix: Implement multi-factor authentication and rate-limiting.
🟣 5. Security Misconfiguration
❌ Issue: Default settings expose sensitive data.
🛠️ Exploitation:
Look for open admin panels (Shodan search)
title:"admin login"Check for sensitive files (.env, .git, .bak, etc.)
curl -X GET https://example.com/.env✅ Fix: Remove unnecessary services, disable default credentials.
🟡 6. Vulnerable & Outdated Components
❌ Issue: Old libraries contain known exploits.
🛠️ Exploitation:
Check versions of frameworks (e.g., WordPress, Django, Laravel)
Look for CVEs in outdated libraries
✅ Fix: Keep software and dependencies updated.
🟠 7. Identification & Authentication Failures
❌ Issue: Weak authentication allows attackers to hijack accounts.
🛠️ Exploitation:
Brute-force login with weak passwords
Check for token reuse
✅ Fix: Implement MFA and secure session management.
🟣 8. Software & Data Integrity Failures
❌ Issue: Unsigned software updates allow tampering.
🛠️ Exploitation:
Modify JavaScript loaded from third-party sources
<script src="http://malicious.com/hack.js"></script>Check for outdated libraries
✅ Fix: Use content security policies (CSP).
🔴 9. Security Logging & Monitoring Failures
❌ Issue: Lack of logs allows undetected attacks.
🛠️ Exploitation:
Bypass security alerts by deleting logs.
Check if brute-force attempts are logged.
✅ Fix: Enable real-time monitoring and alerts.
🔵 10. Server-Side Request Forgery (SSRF)
❌ Issue: Attackers force the server to make requests to internal services.
🛠️ Exploitation:
Test for internal IP access
GET /fetch?url=http://127.0.0.1/adminExploit AWS metadata API
GET /?url=http://169.254.169.254/latest/meta-data/✅ Fix: Restrict external requests, validate input.
Common API Vulnerabilities Beyond OWASP Top 10
Mass Assignment – API allows modifying unintended fields (role=admin).
Rate-Limit Bypass – No restrictions on login attempts.
API Key Exposure – Hardcoded secrets in JavaScript files.
Example: Exposed API Keys in JavaScript
Check:
https://example.com/main.jsIf an API key is found, attackers can abuse it!
✅ Fix: Store secrets securely using environment variables.
Writing a High-Quality Bug Bounty Report
🔹 Format for a Great Report
1️⃣ Title: Clearly state the issue (e.g., Stored XSS leads to account takeover)
2️⃣ Description: Explain the impact and risk level.
3️⃣ Steps to Reproduce: Provide a step-by-step guide with screenshots or a PoC video.
4️⃣ Impact: Describe what an attacker can achieve.
5️⃣ Suggested Fix: Offer practical security recommendations.
Example Report:
Title: IDOR in API allows access to other users’ invoices
Description: The API does not enforce proper authorization, allowing attackers to access invoices of other users.
Steps to Reproduce:
1. Log in to the application
2. Capture the request to `/api/invoice?user_id=123`
3. Modify `user_id=123` to `user_id=124`
4. The system returns another user's invoice
Impact: An attacker can access sensitive financial data.
Suggested Fix: Implement role-based access control (RBAC) and verify user authorization.
Pro Tips for Bug Bounty Success
✔️ Choose low-hanging fruits first – Look for misconfigurations, API issues.
✔️ Automate recon – Use tools like Amass, Subfinder for subdomain discovery.
✔️ Think like an attacker – Identify business logic flaws.
✔️ Write detailed reports – A clear PoC (Proof of Concept) increases bounty rewards.
✔️ Keep learning – Follow top hunters on Twitter, read research papers, join security communities.
