Greg Schneider at The Washington Post reports of problems that Maryland is having with a device available for sale on the Internet that changes red traffic lights to green ones.

Apparently between 1000 and 3000 traffic lights in Maryland have been outfitted with a device that turns them from red to green when they are strobed with an infrared beam. These beams are typically transmitted by police cars and fire engines. The newer devices use a coded beam, but the old devices didn’t — and that’s the problem.

A company in Minnesota is selling a device that transmits the infrared beam, allowing anybody to control the traffic lights. No more red lights! What a cool idea! Unfortunately, it can cause huge traffic jams, accidents, and it’s illegal.

Just another demonstration that it’s not safe to deploy systems with security flaws and hope that nobody will discover them.