Testing for JSON Web Token Vulnerabilities

When to Use

• When testing applications using JWT for authentication and session management
• During API security assessments where JWTs are used for authorization
• When evaluating OAuth 2.0 or OpenID Connect implementations using JWT
• During penetration testing of single sign-on (SSO) systems
• When auditing JWT library configurations for known vulnerabilities

Prerequisites

• jwt_tool (Python JWT exploitation toolkit)
• Burp Suite with JWT Editor extension
• jwt.io for decoding and inspecting JWT structure
• Understanding of JWT structure (header.payload.signature) and algorithms (HS256, RS256)
• hashcat or john for brute-forcing weak JWT secrets
• Python PyJWT library for custom JWT forging scripts
• Access to application using JWT-based authentication