Testing JWT Token Security

When to Use

• During authorized penetration tests when the application uses JWT for authentication or authorization
• When assessing API security where JWTs are passed as Bearer tokens or in cookies
• For evaluating SSO implementations that use JWT/JWS/JWE tokens
• When testing OAuth 2.0 or OpenID Connect flows that issue JWTs
• During security audits of microservice architectures using JWT for inter-service authentication

Prerequisites

• Authorization: Written penetration testing agreement for the target
• jwt_tool: JWT attack toolkit (pip install jwt_tool or git clone https://github.com/ticarpi/jwt_tool.git)
• Burp Suite Professional: With JSON Web Token extension from BApp Store
• Python PyJWT: For scripting custom JWT attacks (pip install pyjwt)
• Hashcat: For brute-forcing HMAC secrets (apt install hashcat)
• jq: For JSON processing
• Target JWT: A valid JWT token from the application