Citigroup breach exposed more accounts than first claimed

Revisionist pwnage report

The security breach that hit the website of Citigroup exposed data for more than 360,000 accounts, the bank said on Wednesday, about 80 percent more than it previously reported.

Citigroup publicly disclosed the compromise last week, but said it involved about 200,000 accounts. Wednesday's revision came amid an inquiry by the Connecticut Attorney General's office, which is one of several state and federal authorities looking into the breach. The hack exposed account holders names, account numbers, and email addresses. It didn't included data typically required in credit card theft, such as the three-digit CVV codes or card expiration dates.

Citi said it discovered the breach on May 10 and immediately rectified the vulnerability that lead to it. It took another two weeks for investigators to determine that customer data had been stolen. The bank has come under criticism for waiting until June 3 to mail notification letters to customers and until June 9 to issue a public statement.

People familiar with the investigation told The New York Times that the attackers gained access to the data by exploiting a garden-variety web flaw in which the hackers changed the numbers in the URLs on the company's website. ®

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