sides tomorrow. today a russian security company reported that it discovered one of the biggest bank robberies ever. no guns involved. hackers did it, breaking into more than 100 banks in 30 countries and making off with a total of as much as $1 billion. here's anna werner. >> reporter: the authors of the report call it "the great bank robbery of the modern era." >> their ultimate goal was to steal as much money as possible, and they largely accomplished that. >> reporter: chris doggett is managing director for kaspersky lab, the computer security firm that uncovered the scheme. h >> your very basic hackers are about getting in and stealing whatever they can get their hands on. the way these guys are different is they were a combination of hackers, spies and thieves. >> reporter: the criminals often used the simplest of methods to get into banks, an e-mail attachment with a virus sent theye to bank employees. when the employee kicked on it the hackers gained access to the bank's financial system, and