Hunting Hidden Endpoints: Advanced Techniques for Bug Bounty

Introduction:

Hidden endpoints often contain sensitive functionalities, unreleased features, or admin-only actions. Finding these endpoints can lead to IDORs, privilege escalations, and critical business logic flaws. Let’s explore advanced techniques to uncover them.

1. Passive Discovery with JavaScript Analysis

Tool: LinkFinder

Method : Extract URLs from JavaScript files using regex-based scanning.

Example Command :

python3 linkfinder.py -i https://target.com/script.js -o cli

Tip: Look for endpoints like /admin, /debug, /beta, or unusual API routes.

2. Fuzzing for Undocumented APIs

Tool : ffuf

Method: Brute-force directories and API endpoints using wordlists.

Example Command :

ffuf -u https://target.com/FUZZ -w wordlist.txt -mc 200,302

Tip: Use custom wordlists for API discovery (e.g., SecLists/API directory).

3. CSP & CORS Misconfigurations to Find Hidden Domains

Tool: Corsy

Method: Extract additional subdomains or private API servers from Content Security Policy (CSP) and CORS headers.

Example Command:

python3 corsy.py -u https://target.com

Tip: Look for wildcard policies (*.target.com) that might expose internal systems.

4. Log File & Debug Mode Exposure

Method: Search for exposed .log, .env, .config, and debug mode indicators.

Example:

curl -s -X GET https://target.com/debug.log

Tip: Some apps expose API keys, admin credentials, or internal endpoints in logs.

5. Burp Suite Extensions for Endpoint Discovery

Extension: Param Miner (Find hidden parameters & endpoints)

Usage:

1. Load the extension in Burp Suite → Extender → BApp Store

2. Right-click a request → Guess Hidden Parameters

Tip: Test for ?debug=true, ?beta=1, ?admin=1, and other flags that reveal hidden routes.

Final Thoughts:

Finding hidden endpoints gives early access to new features, admin panels, and internal APIs, making them a goldmine for bug bounty hunters. Automate your recon, but don’t forget to manually inspect JavaScript and API responses for clues.