WASHINGTON _ Marriott Hotels has learned the hard way from the saying that there are two types of businesses: Those that have been hacked and those that may not yet know they've been hacked.
For four years, Marriott Hotels fell in the latter category. Buried in Marriott's announcement Friday that personal data of as many as 500 million guests was lost in the second largest consumer breach in U.S. history, the company said hackers first entered the guest reservation systems in 2014.
The hack remained undetected year after year.
