Business logic bugs are sneaky. They’re not about crashing servers or SQLi, but about using an app exactly as intended but in a way that breaks the business.

During reconnaissance I observed that many YWH/HackerOne programs implement some rudimentary checks to filter payment test card credentials on production environment.

While carrying out a Bug hunt on Spacelift on YWH, I attempted the payment flow using test card credentials against the production checkout and guess what? The gateway accepted the test card, indicating the payment integration was operating in test mode or insufficiently validating live tokens.

Why is this an issue?

Any platform that allows test card credentials to go through without any checks to confirm whether the details are real shows a serious flaw.

Observing this and comparing it with other sites, I notice the business logic assumed any “attempted” payment was valid, without verifying the actual transaction status of the card.

Tips:

Always check for simple test credential validation on production environments. Some programs may consider it a flaw, while others may not. However, this remains a crucial logic issue worth verifying in every target.

Reference:

https://shahjerry33.medium.com/business-logic-errors-art-of-testing-cards-4907cfb46a57

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