Promo abuse is hard to detect because it mimics the activities of regular users, at least at first.
A given user signing up for a new account, claiming a promotion, and making a purchase with that discount is what marketing teams are expecting to happen. Some legitimate new users don’t stick around after claiming a promotion—maybe they don’t like the full price of the service, maybe they prefer a competitor, maybe they tried the service itself and didn’t like it. Whatever the reason, it’s perfectly normal user behavior to see a new account that claims a promotion, makes an order, and then doesn’t order anything else.
The difference between regular users and fraudsters is, of course, that the fraudsters repeat this process dozens or hundreds of times to take advantage of the platform. But if the platform doesn’t realize that all of the fraudsters’ accounts belong to the same user, their behavior mimics typical customer churn.
This account-to-user binding problem brings us to the next big challenge of detecting promo abuse: weak device ID solutions. Many platforms rely on legacy or internally-built device fingerprinting solutions that aren’t resilient enough to keep identifying a user’s device after that user takes obfuscation measures. Something as simple as reinstalling the app or factory resetting the device can be enough to fool many legacy device IDs into seeing many different devices where there is only one or two. App tampering tools, app cloners, and emulators are also useful tools in creating the appearance of multiple devices so that fraudsters can make as many fresh user accounts as they want.
Even if a platform’s device ID is strong enough to block multi-accounting attempts, some organized fraudsters have multiple devices at their disposal, forming what we call a “fraud farm” or “device farm.”
In order to stop the same user from making multiple accounts with a platform, a platform must be able to persistently bind a user’s device to their identity, even when the same user has multiple devices.