Great point. This does seem like an important vulnerability.
I think one method of protection would be using Stripes Radar service to screen transactions for malicious patterns.
While it probably won’t catch all fraudulent charges, it’ll catch a bunch. You can use that increase in rejected transactions as a canary to take a closer look at the other transactions coming through.
Does anyone else have ideas on how you can protect yourself from this kind of attack?
Edit: thinking about this more, it would be a pretty expensive attack to attempt. Stolen credit cards aren't cheap, like email addresses are. You'd need a lot of them to attempt the attack and you likely wouldn't succeed.
I think you'd need 1% of the target merchant's transactions to be chargebacks in order to get them kicked off. I'd assume at least 50% of your attempts would get caught before the chargeback even happens, so you'd need at least 2% of their transactions.
Seems like you'd need a large number of cards. Anyone know the value of a stolen card?