Source:
New York Times Hackers have stolen credit card information for customers who shopped as recently as last month at 63 Barnes & Noble stores across the country, including stores in New York City, San Diego, Miami and Chicago, according to people briefed on the investigation.
The company discovered around Sept. 14 that the information had been stolen but kept the matter quiet at the Justice Department’s request so the F.B.I. could determine who was behind the attacks, according to these people.
... The official defended the company’s decision not to tell its customers about the attack, saying that the company had informed credit card companies that certain accounts might have been compromised.
... “This is no small undertaking,” said Edward Schwartz, the chief security officer at RSA, a security company. “An attack of this type involves many different phases of reconnaissance and multiple levels of exploitation.”
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http://www.nytimes.com/2012/10/24/business/hackers-get-credit-data-at-barnes-noble.html