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.

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.

If you’re staying at hotel, it might be a good idea to check the manufacturer of your door lock. A black hat hacker has unveiled a method that allows a fairly simple hardware gadget to unlock door ...