The names, banks and account numbers of up to 40 million credit card holders may have been accessed by an unauthorized user, MasterCard International Inc. said Friday.
The credit card giant said the security breach involves a computer virus that captured customer data for the purpose of fraud and may have affected holders of all brands of credit cards.
It said the breach was traced to Atlanta-based CardSystems Solutions Inc., which processes credit card and other payments for banks and merchants.
The compromised data did not include addresses or Social Security numbers, said MasterCard spokeswoman Sharon Gamsin. The data that may have been viewed - names, banks and account numbers - could be used to steal funds but not identities.
Gamsin said she did not know how a viruslike computer script that captured customer data got into CardSystems' network, which MasterCard said was infiltrated by an unauthorized individual. Neither company would elaborate.
The FBI was investigating.
The incident was the latest in a series of security breaches affecting valuable consumer data at major financial institutions and data brokers in an increasingly database-driven world.
The breach appears to be the largest yet involving financial data, said David Sobel, general counsel at the Electronic Privacy Information Center.
"The steady stream of these disclosures shows the pressing need for regulation of the industry both in terms of limitation in the amount of personal information that companies collect and also liability when these kinds of disclosures occur," Sobel said.
A flurry of disclosures of breaches affecting high-profile companies including Citigroup Inc., Bank of America Corp. and DSW Shoe Warehouse has prompted federal lawmakers to draw up legislation designed to better protect consumer privacy.
MasterCard, which said about 14 million of its own cards were exposed, first announced the breach Friday afternoon, saying it was notifying its card-issuing banks of the problem.
However, CardSystems said late Friday in a statement vetted by the FBI that it first learned of a potential breach on May 22. It said it was told by the FBI not to release any information to the public. The company said it was surprised by MasterCard's decision to go public.
"We were absolutely blindsided by a press release by the association," CardSystems' chief financial officer, Michael Brady, said when reached on his cell phone. He refused to answer any questions and referred calls to the company's chief executive, John Perry, and its senior vice president of marketing, Bill Reeves.
Reeves said the information the company gathered initially was "on a need-to-know basis." He said he could not comment beyond a company statement, which did not give any details about the breach but noted that CardSystems is implementing increased security measures.
"I understand and fully appreciate the seriousness of the situation," Reeves said.
Under federal law, credit card holders are liable for no more than $50 of unauthorized charges, and many card issuers including MasterCard will even waive the $50.
CardSystems processes less than 0.5 percent of American Express' domestic transactions, said company spokeswoman Judy Tenzer. She said a small number of its cardholders were affected, though she did not have an exact figure. Discover Financial Services Inc. said it was aware of the situation and would not say whether any of its cards were involved. Visa USA and a large issuer of cards, MBNA Corp., did not immediately calls seeking comment.
CardSystems, which has a processing center in Tucson, Ariz., has been in business for more than 15 years and handles transactions for more than 115,000 small to midsized businesses, according to the company's Web site. The company says it processes transactions worth more than $15 billion annually. Sobel said the fact that the latest breach involved a third party "indicates that this is a shadowy industry where the consumer never really knows who is going to be handling and using their personal information."
Earlier this month, Citigroup said UPS lost computer tapes with sensitive information from 3.9 million customers of CitiFinancial, a unit that provides personal and home loans.