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How I Made $6,000 by Exploiting JWT Manipulation on a Web3 Crypto App 💰💻

Krish_cyber
Cyber Security Write-ups

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🔥 The $6,000 Bug Bounty Story

A few months ago, while hunting for vulnerabilities in Web3 applications, I stumbled upon a critical JWT (JSON Web Token) manipulation bug that led to a $6,000 bounty payout! 🚀 If you’re into bug bounty hunting, cybersecurity, or Web3 security, you’ll love this breakdown of how I found, exploited, and reported this issue.

🧐 What is JWT and Why Does It Matter?

JWT (JSON Web Token) is widely used for authentication in Web3 and traditional web applications. It’s a compact, URL-safe token that stores claims between parties. A typical JWT looks like this:

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VyX2lkIjoxMjM0NTYsImFkbWluIjpmYWxzZX0.7QDfCe1D7sPdX9Dg3pYMLkx_1J1G

This token has three parts:

  1. Header — Contains the algorithm and token type.
  2. Payload — Contains the claims (e.g., user ID, roles).
  3. Signature — Ensures the token’s integrity.

When implemented correctly, JWT ensures secure authentication. However, misconfigurations can make it a hacker’s playground. 🎯

🔎 Finding the Vulnerability — The JWT…

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Published in Cyber Security Write-ups

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Written by Krish_cyber

hii I'm krishna passionate cybersecurity enthusiast and aspiring bug bounty hunter, dedicated to ethical hacking and securing digital system.

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