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Dictionary attack: Symmetric Signing Algorithms

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

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Lab Walkthrough Video:


The 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. Another important factor is the strength of the secret key used for signing the tokens. This challenge is all about bruteforcing the weak JWT secret key used by the REST API.

Objective: Determine the secret key and leverage it to read the flag stored on the target server.

User Information:

Usernameelliot
Password
elliotalderson
Email
elliot@evilcorp.com

API Endpoints:

Endpoint
Description
Method
Parameter(s)
/auth/local
Authenticates the user and returns JWT authentication token
POST
identifier, password
/users
Creates a new user
POST
username, password, email, role, provider
/admin
Access Strapi Admin Panel
GET
-

Instructions: 

  • 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.
  • Do not attack the gateway located at IP address 192.X.Y.1
  • The secret key has 4 digits, each from the range of 0 to 9.
  • jwtcat, the tool required to crack the secret key is present in "/root/Desktop/tools/" directory


Verify:
1. Flag
 

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