"They get the list of usernames and passwords and then they go and start trying those on Bank of America, on Gmail," Electronic Frontier Foundation spokesperson Seth Schoen said.

Schoen studies Internet scams. He says predators who get your username and password from one site will try the same log-in to break into all your other accounts.

"This happens every day because people are re-using account names and passwords from one site to another," Schoen said.