Increasingly, criminals with sophisticated tools are actively targeting vulnerable merchant point-of-sale (POS) terminals to steal payment card data and PINs for counterfeit fraud purposes. Criminal gangs worldwide are illegally accessing active POS terminals and modifying them by inserting an undetectable electronic “bug” that captures cardholder data and PINs during normal transaction processing.
Visa has released an excellent bulletin all brick and mortar merchants should read.
Point-of-Sale Terminal Tampering (pdf download)
Is a Crime . . .
and You Can Stop It