Remember that episode of Leverage (season 5, episode 3), where Alec uses Marvin to wirelessly change all the street lights green so they can catch up to an SUV? And you scoffed and said “that’s so not real!”… well actually they got it right. A new study out of the University of Michigan (PDF warning), shows just how easy it is to make your morning commute green lights all the way.

The study points out that a large portion of traffic lights in the United States communicate with each other wirelessly over the 900Mhz and 5.8Ghz ISM band with absolutely no encryption. In order to connect to the 5.8Ghz traffic signals, you simply need the SSID (which is set to broadcast) and the proper protocol. In the study the researchers used a wireless card that is not available to the public, but they do point out that with a bit of social engineering you could probably get one. Another route is the HackRF SDR, which could be used to both sniff and transmit the required protocol. Once connected to the network you will need the default username and password, which can be found on the traffic light manufacturer’s website. To gain access to the 900Mhz networks you need all of the above and a 16-bit slave ID. This can be brute forced, and as the study shows, no ID was greater than 100. Now you have full access, not to just one traffic signal, but EVERY signal connected to the network.

Once on the network you have two options. The completely open debug port in the VxWorks OS which allows you to read-modify-write any memory register. Or by sending a(n) UDP packet where the last byte encodes the button pressed on the controller’s keypad. Using the remote keypad you can freeze the current intersection state, modify the signal timing, or change the state of any light. However the hardware Malfunction Management Unit (MMU) will still detect any illegal states (conflicting green or yellow lights), and take over with the familiar 4-way red flashing. Since a technician will have to come out and manually reset the traffic signal to recover from an illegal state, you could turn every intersection on the network into a 4-way stop.

So the next time you stop at a red light, and it seems to take forever to change, keep an eye out for the hacker who just green lit their commute.

Thanks for the tip [Matt]