The Sony data breach, which exposed information from more than 100 million user accounts in April, could prove to be the mostly costly data breach of all time. Hackers obtained personal information, including credit, debit, and bank account numbers in some instances, of PlayStation Network users and Sony Online Entertainment users. After discovering there had been a breach, Sony shut down both networks temporarily. Ponemon estimates that the breach could cost Sony and credit card issuers up to a total of $2 billion.
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