Fraud runs rampant with Apple iPhones and thieves are constantly coming up with ways to make money off of the devices. The company has been fighting viciously to reduce how successful these attempts are, especially in countries where fraud is abnormally high, such as China.

One of these complex schemes involves taking the valuable and expensive inside components such as the processor or motherboard and replacing them with broken parts. Fraudsters would then take the iPhones back to the store and claim that they needed iPhone repair, receive a replacement, and resell the device.

Apple initially released software that retail employees could use to diagnose whether an iPhone contained fake parts. Fraudsters responded by disabling the phones to prevent employees from being able to figure out that they’d replaced these parts since they weren’t able to run the software. They didn’t stop there. The next tactic involved finding serial numbers for phones already sold in China and etching these on the iPhones themselves.

The company counteracted these measures by launching what they called “Zombie Check” that could determine whether the phone tied to that serial number was previously linked to online services such as iCloud. Its initial release was limited to China, but they allowed authorized service providers to access the feature worldwide back in February 2019.

The tool, simply known as a Serial Number Reader, is rather basic and has a Lightning connector on one end and USB-A on the opposite end. It works on an iPhone 6 or newer and obtains the serial number right from the logic board, limiting options for scammers. An employee only needs to hook the cord to a Mac and run the companion tool, which should pop the number up even if the phone doesn’t power on. It also works if the phone has endured water damage.

Documents produced by Apple internally reveal that the purpose of the validation is to ensure that warranties and services are only available to genuine Apple devices. The added security can thwart fraudsters and require those trying to obtain warranty services fraudulently to find an alternate method.

The tool seems to be effective. Apple reported on their most recent 10-K form, released annually that their expenses for warranty and repairs was $4.32 billion. Costs for the previous year amounted to a whopping $4.66 billion. It seems Apple is on the right track to cut costs.