Bad news: With less than $50 of off-the-shelf hardware and a little bit of programming, it's possible for a hacker to gain instant, untraceable access to millions of key card-protected hotel rooms.

A string of break-ins at a Houston hotel are being blamed on hackers who exploited a flaw in room locks, a vulnerability that was exposed this year at the Black Hat Security Conference in Las Vegas.

Forget jumping on the bed. The first thing you should do when you book a hotel room is check the locks. A small new tool is allowing thieves to break into locked hotel rooms at some of the most ...