A common vulnerability where concurrent process leads to uninted behaviour,

Limit overrun race conditions

Enables you to exceed some kind of limit imposed by the business logic of the application.

What would happen if a user who has never applied this discount code before tried to apply it twice at almost exactly the same time:

https://portswigger.net/web-security/learning-paths/race-conditions/race-conditions-limit-overrun/race-conditions/limit-overrun-race-conditions-r6f5

the application transitions through a temporary sub-state; that is, a state that it enters and then exits again before request processing is complete. In this case, the sub-state begins when the server starts processing the first request, and ends when it updates the database to indicate that you’ve already used this code. This introduces a small race window during which you can repeatedly claim the discount as many times as you like.

There are many variations of this kind of attack, including:

  • Redeeming a gift card multiple times
  • Rating a product multiple times
  • Withdrawing or transferring cash in excess of your account balance
  • Reusing a single CAPTCHA solution
  • Bypassing an anti-brute-force rate limit

Repeater can do - using single tcp packet and network jitter - 2023.9

Sending grouped HTTP requests

https://portswigger.net/burp/documentation/desktop/tools/repeater/send-group

Turbo intruder


https://portswigger.net/web-security/learning-paths/race-conditions/race-conditions-detecting-and-exploiting-with-turbo-intruder/race-conditions/detecting-and-exploiting-limit-overrun-race-conditions-with-turbo-intruder-c3d4

https://portswigger.net/web-security/race-conditions/lab-race-conditions-limit-overrun