Earlier this month officials from Citigroup confirmed that an unauthorized network access event compromised the private account details of over 360,000 of North American banking clients.
Officials from the banking giant now assert that $2.7 million was stolen from about 3,400 accounts in the May attack.
“Customers are not liable for any fraud on the accounts and are 100 percent protected,“ the bank said.
Representatives of Citigroup said they detected the breach of the Citi Account Online network through routine monitoring of the systems. It appears that only credit card accounts were exposed in the breach, though some reports suggest that some debit card information may have been involved.
“From the moment Citi discovered the breach, we took immediate action to rectify the situation and protect any customers potentially at risk,“ Citi officials said in an earlier statement.
Citigroup immediately reported the security incident to law enforcement and regulatory authorities, but waited about three weeks before beginning the process of notifying potentially affected customers.
The Citigroup breach is considered one of the very few successful hacks against a major banks systems, and underscores the need for continued vigilance by financial institutions and their clients where security best practices are concerned.