The hackers who breached JP Morgan Chase's defense this summer burrowed deep into the bank's internal computer systems.
On its website, Chase says, "there is no evidence account numbers, passwords or social security numbers were compromised." But the attack showed that even the nation's largest bank is vulnerable.
Meg Whitman, CEO of tech giant Hewlett Packard, said in an interview this summer that the threat is growing every day.
"This is no longer teenagers," says Whitman. "This is very serious organized crime nation states that are trying to do real damage."
"This is a real and present danger," said Whitman. "You've got to be on this in a way most companies haven't been for the last four or five years and it's an arms race. Bad guys get better, we've got to get better."
Security experts say that bank customers have to be relentless too, especially when they know their information has been compromised.
Matt Schultz of CreditCards.com said that even the smallest changes on account statements should be scrutinized.
Schulz said this information "can be out there for a really long time."
"It can be a $2 purchase at a gas station that you may kind of blow off," said Schultz. "But often times fraudsters will do little purchases like that to test the card to see if it's valid and if the number works."
Seventy-six million names, addresses and emails were compromised in the Chase breach. Identifty theft criminals can use that information to pretend to be your bank and try to "phish" for your account number.
Even if Chase's system is now secure, your information may not be.