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Bypassing NBF Claim

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

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Lab Walkthrough Video:

The NBF (not before) claim identifies the time before which a JWT Token must not be accepted for processing. The processing of the NBF claim requires that the current date/time must be after or equal to the not-before date/time.

Dummy Bank had created an application called GenerateTicket to generate a JWT token embedded in a QR-Code.
The generated token will used to authenticate the users on the bank server and let them enroll into a new scheme that will be launched after 3 days.
The first person to be enrolled into that scheme would receive a Golden Ticket as a reward.

Objective: Your task is to get the Golden Ticket.


  • file contains some basic instructions for the challenge.
  • 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.
  • zbarimg, the tool required to decode the QR code is pre-installed in the Ubuntu instance.
  • The bank server should be running on port 8080 on the machine located at the IP address 192.X.Y.3.

1. Golden Ticket

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