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Scope of TJX data breach doubles: 94M cards now said to be affected

The company at first said 45.6M accounts had been breached

October 24, 2007 12:00 PM ET

Computerworld - For anyone who thought that 45 million was an absurdly high number of payment cards to be compromised in a data breach, try 94 million.

That's the total number of cards actually exposed in the breach disclosed by TJX Companies Inc. earlier this year, according to court documents filed yesterday by a group of banks suing the Framingham, Mass.-based retailer over the incident.

The filings, made in federal court in Boston, relate to a dispute over whether the multiple financial institutions who are plaintiffs in the case should be treated as a class or whether each bank would be required to pursue individual cases against TJX. The plaintiffs in the case include the Massachusetts Bankers Association, the Connecticut Bankers Association, the Maine Association of Community Banks and AmeriFirst Bank Inc.

In documents arguing for class action status, the banks claim that the TJX breach affected 94 million separate card holder accounts over a 17-month period -- not 45.6 million accounts, as TJX had disclosed. Quoting figures supplied by the card companies themselves, the bankers said that the breach affected approximately 65 million Visa account numbers and an additional 29 million MasterCard accounts. To date, the losses by card-issuing companies on Visa accounts alone total between $68 million and $83 million, the banks said, citing the Visa information.

"Unlike other limited data breaches where 'pastime hackers' may have accessed data with no intention to commit fraud, in this case it is beyond doubt that there is an extremely high risk that the compromised data will be used for illegal purposes," the bankers said in an affidavit. "Faced with overwhelming exposure to losses it created, TJX continues to downplay the seriousness of the situation."

TJX officials did not immediately respond to a request for comment.

The figures included in the court documents, if accurate, more than double the size of the TJX breach, which had originally been pegged at 45.6 million cards based on estimates from the retailer itself. Even that number represented the biggest-ever compromise of payment card data. The next-closest data compromise is the mid-2005 breach at CardSystems Solutions Inc., which involved about 40 million cards.

The large discrepancy between the numbers supplied by TJX and those from the banks suggest that TJX did not have the log data needed to do a proper forensic analysis of the incident, said Michael Maloof, chief technology officer at Trigeo Network Security Inc., a vendor of security event management tools in Post Falls, Idaho. All too often, he said, companies that don't have processes in place for collecting and storing log data wind up losing the telltale tracks left behind by computer intrusions.

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