Back to Labs

JWT Security Lab

🎯Learning Objective: JWT Vulnerabilities

JSON Web Tokens (JWT) are widely used for authentication and authorization. This lab demonstrates common JWT vulnerabilities including algorithm confusion, weak secrets, and payload manipulation attacks.

Attack Vectors:

  • • Algorithm confusion attacks
  • • Weak secret exploitation
  • • Signature stripping
  • • Payload manipulation

Security Focus:

  • • Proper algorithm validation
  • • Strong secret management
  • • Signature verification
  • • Claim validation

Current JWT Token

Attack Vector

JWT Decoder & Tester

Quick Actions

Standard JWT Structure

Standard JWT Token

Properly signed JWT with HMAC-SHA256

// Header
{"alg":"HS256","typ":"JWT"}

// Payload  
{"sub":"alice","role":"user","admin":false,"iat":1640995200}

// Signature: HMACSHA256(base64UrlEncode(header) + "." + base64UrlEncode(payload), secret)

🛡️JWT Security Best Practices