A KrebsOnSecurity story last month about credit card skimmers found in self-checkout lanes at some Walmart locations got picked up by quite a few publications. Since then I’ve heard from several readers who work at retailers that use hundreds of thousands of these Ingenico credit card terminals across their stores, and all wanted to know the same thing: How could they tell if their self-checkout lanes were compromised? This post provides a few pointers.
Happily, just days before my story point-of-sale vendor Ingenico produced a tutorial on how to spot a skimmer on self checkout lanes powered by Ingenico iSC250 card terminals. Unfortunately, it doesn’t appear that this report was widely disseminated, because I’m still getting questions from readers at retailers that use these devices.
“In order for the overlay to fit atop the POS [point-of-sale] terminal, it must be longer and wider than the target device,” reads a May 16, 2016 security bulletin obtained by KrebsOnSecurity. “For this reason, the case overlay will appear noticeably larger than the actual POS terminal. This is the primary identifying characteristic of the skimming device. A skimmer overlay of the iSC250 is over 6 inches wide and 7 inches tall while the iSC250 itself is 5 9/16 inch wide and 6 1⁄2 inches tall.”
In addition, the skimming device that thieves can attach in the blink of an eye on top of the Ingenico self-checkout card reader blocks the backlight from coming through the fake PIN pad overlay.