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Introduction:
The world of bug bounty hunting is no longer a niche playground for elite hackers; it is a critical front line in modern cybersecurity defense. A recent reward of $3,000,000 IDR (approximately $200 USD) to a student researcher for a single vulnerability report underscores a massive shift in how organizations source their security intelligence. This paradigm move from internal audits to crowd-sourced ethical hacking demonstrates that continuous, adversarial testing is the only way to fortify digital assets against evolving threats.
Learning Objectives:
- Understand the core methodologies and tools used by successful bug bounty hunters to identify common web application vulnerabilities.
- Learn to replicate and test for critical flaws like SQL Injection, Cross-Site Scripting (XSS), and insecure direct object references (IDOR) in a controlled environment.
- Develop a structured approach to documenting and reporting vulnerabilities to bug bounty platforms to ensure they are properly understood and patched.
You Should Know:
1. Reconnaissance: The Art of Discovering Hidden Endpoints
Before any attack can be simulated, a hunter must map the target application. This involves discovering subdomains, directories, and API endpoints that are not publicly linked.
Command (CLI - Subfinder): subfinder -d target.com -o subdomains.txt Command (CLI - httpx): cat subdomains.txt | httpx -silent -status-code -o live_urls.txt
Step-by-step guide: Subfinder is a passive subdomain discovery tool. The first command queries multiple sources to find subdomains for `target.com` and saves them. The second command, using httpx, takes that list, probes each one to see if it’s live, and returns the HTTP status code. This quickly narrows down thousands of possibilities to a handful of active, interesting targets for manual testing.
2. Injecting for Impact: Classic SQL Injection Testing
SQL Injection (SQLi) remains a top vulnerability, allowing attackers to interfere with an application’s database queries, often leading to data exposure.
Command (CLI - with SQLmap): sqlmap -u "https://target.com/login?id=1" --batch --dbs Manual Test Payload: https://target.com/user?id=1' https://target.com/user?id=1 OR 1=1--
Step-by-step guide: The `sqlmap` command automates the process of detecting and exploiting SQLi flaws. The `-u` flag specifies the target URL, and `–dbs` attempts to enumerate available databases. For manual testing, appending a single quote (') often causes a database error, indicating a potential flaw. The `OR 1=1–` payload then tests if the query can be manipulated to return all records.
3. Cross-Site Scripting: Hijacking User Sessions
XSS vulnerabilities allow attackers to execute malicious scripts in a victim’s browser, potentially stealing cookies, sessions, or defacing websites.
Test Payload (Reflected XSS):
<script>alert('XSS')</script>
Test Payload (DOM-based XSS):
"><img src=x onerror=alert('DOM-XSS')>
Step-by-step guide: To test for Reflected XSS, find a search field or URL parameter and submit the basic `