Target cyber breach hits 40 million payment cards at holiday peak --- (Reuters) - Target Corp said hackers have stolen data from up to 40 million credit and debit cards of shoppers who visited its stores during the first three weeks of the holiday season in the second-largest such breach reported by a U.S. retailer. -- The hackers worked at unprecedented speed, carrying out their operation from the day before Thanksgiving to this past Sunday, 19 days that are the heart of the crucial Christmas holiday sales season. -- Target, the third-largest U.S. retailer, said on Thursday that it was working with federal law enforcement and outside experts to prevent similar attacks in the future. It did not disclose how its systems were compromised. -- The retailer was alerted its systems might have been compromised by credit card processors who had noticed a surge in fraudulent transactions involving credit cards that had been used at Target, according to a person familiar with the investigation who was not authorized to discuss the matter. - More, at: http://www.reuters.com/article/2013/12/20/us-target-breach-idUSBRE9BH1GX20131220