Target Corporation confirmed that cyber thieves stole credit and debit card data belonging to about 40 million customers who used those cards at its stores nationwide beginning around Thanksgiving and through mid-December, says the Christian Science Monitor. That the thieves were able to defeat increased cyber-security measures, experts warn, is a worrying sign that cyber criminals' sophistication is keeping them one step ahead of the retail industry and law enforcement officials. The stolen data, contained on magnetic strips on the back of cards, include the customer's name, the credit or debit card number, and the card's expiration date – as well as the “CVV” or three-digit security code. Such “track data” are gathered and sold in black market websites. Later they can be used to create fake credit cards to charge merchandise at a store, withdraw cash from an ATM, or charge merchandise online. The data in question appear to have been stolen from Target's brick-and-mortar stores without affecting the company's online operations, said Brian Krebs, the online security blogger who revealed the breach.