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Burp Extender

Burp Extender lets you extend the functionality of Burp Suite in numerous ways.

Extensions can be written in Java, Python or Ruby.

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  3. JSON Web Token Attacker

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 1.0.2
Last updated 08 February 2019

You can install BApps directly within Burp, via the BApp Store feature in the Burp Extender tool. You can also download them from here, for offline installation into Burp.

You can view the source code for this BApp by visiting our GitHub page.
Follow @BApp_Store on Twitter to receive notifications of all BApp releases and updates.
Download BApp

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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