According to the internal Secret Service memo Krebs got his hands on, credit card thieves are using smart cards to avoid raising suspicion. Someone changing the numbers used on a single smart card after a transaction has been declined will look less suspicious than someone rifling through dozens of physical cards, after all.

Krebs notes that fraud rings would often purchase thousands of stolen debit and credit card data, which were mostly obtained through skimmers and hacked point-of-sale devices, online. They can easily use those numbers with a smart card. That said, the Secret Service's memo explained that "smart card technology makes up a small portion of fraudulent credit cards" at the moment. It's not entirely clear if smart card makers can implement additional safety measures to prevent the use of stolen data, so in the end, all you can do is keep a close eye on your credit card statements.