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Verification Key Mismanagement II

rest-jwt-advanced | Level: Easy  | Total Lab Runs: 0 | Premium Lab

Lab Scoreboard

Lab Walkthrough Video:

A REST API is running on the target machine and uses JWT based authentication. The implementation of JWT is very crucial for the safety of an API. The API uses the JWT library implementation that is vulnerable to the issue documented in CVE-2016-10555.

The server uses RS256 algorithm as the default signing algorithm to generate the tokens.

Objective: Retrieve the flag stored on the target server.

User Information:


API Endpoints:

Authenticates the user and returns JWT authentication token
identifier, password
Creates a new user
username, password, email, role, provider
Access Strapi Admin Panel


  • This lab is dedicated to you! No other users are on this network :)
  • Once you start the lab, you will have access to a Kali GUI instance.
  • Your Kali instance has an interface with IP address 192.X.Y.2. Run "ifconfig" to know the values of X and Y.
  • The REST API should be running on port 1337 on the machine located at the IP address 192.X.Y.3.
  • The public key used to verify the JWT token generated by the target server is provided in the GUI instance in the root directory.
  • PyJWT, the library used to work with JWT Tokens is provided in the GUI instance.
  • Do not attack the gateway located at IP address 192.X.Y.1

You can find everything you need for the challenge on the token issuer's website.

All relevant information to solve this lab is available on the CVE website.

1. Flag

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Technical Support for this Lab:

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