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JSON Web Token Attacker

JOSEPH - JavaScript Object Signing and Encryption Pentesting Helper

This extension helps to test applications that use JavaScript Object Signing and Encryption, including JSON Web Tokens.


  • Recognition and marking
  • JWS/JWE editors
  • (Semi-)Automated attacks
    • Bleichenbacher MMA
    • Key Confusion (aka Algorithm Substitution)
    • Signature Exclusion
  • Base64url en-/decoder
  • Easy extensibility of new attacks
Author Dennis Detering
Version 1.0.2a
Last updated 04 February 2022

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Please note that extensions are written by third party users of Burp, and PortSwigger Web Security makes no warranty about their quality or usefulness for any particular purpose.

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