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JWTweak - JSON Web Token [JWT] Algorithm Convertor and Generator Tool

Introduction

With the global increase in JSON Web Token (JWT) usage, the attack surface has also increased significantly. Having said that, this utility is designed with the aim to generate the new JWT token with little or no time which would help security enthusiasts to find security flaws in JWT implementation like JWT Algorithm Confusion Attack. This tool is designed to automate the process of modifying the JWT algorithm of input JWT Token and then generate the new JWT based on the new algorithm.

Requirements

Python 3 (tested and working fine in python-3.7.7/Kali and python-3.8.2/Windows 10)
pip3 install pycryptodomex

Features

  • Detects the algorithm of the input JWT Token
  • Base64 decode the input JWT Token
  • Generate new JWT by changing the algorithm of the input JWT to ‘none’
  • Generate new JWT by changing the algorithm of the input JWT to ‘HS256’
  • Generate new JWT by changing the algorithm of the input JWT to ‘HS384’
  • Generate new JWT by changing the algorithm of the input JWT to ‘HS512’
  • Generate new JWT by changing the algorithm of the input JWT to ‘RS256’
  • Generate new JWT by changing the algorithm of the input JWT to ‘RS384’
  • Generate new JWT by changing the algorithm of the input JWT to ‘RS512’

Download Link  - JWTweak.py

POC



[Disclaimer - For Education and Ethical Security Testing Purpose - Case study, attacks' scenarios and audit guidelines on vulnerabilities]

Security blog of the month

JWTweak v2.1 – A Guided, Offline Toolkit for Modern JWT Attacks

Introduction JSON Web Tokens sit at the heart of modern authentication – and because the token travels in the user’s hands, a single weak check on the server side can hand an attacker an admin account. JWTweak was built to test for exactly these flaws. It started as a small utility to switch a token’s algorithm and re-issue it in seconds, helping security enthusiasts hunt for issues like the JWT Algorithm Confusion Attack. Version 2.1 is a complete rewrite into a guided, menu-driven toolkit: you paste a token, it decodes and risk-analyses it, recommends the attacks that fit, and walks you through each one – entirely offline, with no flags to memorise. In this post we’ll tour the tool and then break into a deliberately vulnerable app with two live proof-of-concept attacks.
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