🔓 How I Find Hidden API Bugs Most Hackers Miss

Most hackers test what they can see.

👉 Login page 👉 Dashboard 👉 Forms

And ignore the most important part:

👉 APIs

That's where real bugs live.

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🧠 Why APIs Are Goldmine

Modern applications are built on APIs:

- Mobile apps - Single Page Apps (SPA) - Backend services

👉 Everything talks through APIs

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💥 Problem

Developers often:

- Trust frontend too much - Skip backend validation - Miss authorization checks

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👉 Result: Hidden vulnerabilities

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🔍 Step 1: Find API Endpoints

🎯 Where to Look

- Browser DevTools → Network tab - JavaScript files - Mobile apps

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💡 Example

GET /api/user/profile?id=1001

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👉 This is your entry point

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⚡ Step 2: Understand the Request

Ask:

- What data is being sent? - What parameters exist? - What should be restricted?

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👉 Don't rush to test

👉 First understand

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💣 Step 3: Test Authorization (MOST IMPORTANT)

Change:

?id=1001 → ?id=1002

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👉 Check:

- Do you get another user's data?

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💥 If yes → IDOR

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🔐 Step 4: Test Hidden Parameters

Sometimes APIs accept more than shown.

Try adding:

"user_id": 2000 "role": "admin"

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👉 Developers forget to validate these

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🔄 Step 5: Replay Requests

- Logout - Send same request

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👉 If still works:

💥 Missing authentication

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🧠 Step 6: Look for Patterns

If one API works:

👉 Others might too

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Example:

- "/api/user" - "/api/order" - "/api/invoice"

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👉 Test all

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💥 Real Bug Scenario

Found:

GET /api/orders?id=5001

Changed:

?id=5002

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👉 Got another user's order

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💣 Impact:

- Data leak - Privacy issue - Possible account takeover

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⚡ Pro Tips

- Always test APIs 🔥 - Ignore UI restrictions - Think backend, not frontend

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❌ Common Mistakes

- Testing only frontend - Ignoring API calls - Not modifying requests

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🚀 Action Plan

Today:

1. Open any website 2. Go to DevTools → Network 3. Find API 4. Modify request 5. Test

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👉 That's it

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🏁 Final Thoughts

Most bugs are not visible.

👉 They are hidden in APIs

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💬 Start testing APIs today.

👉 You'll find what others miss.

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🚀 That's how real bug hunters work.