Status: 07.12.2022 06:00 a.m
Many traffic light systems in the north can apparently be manipulated. This was shown by IT experts NDR, BR and the computer magazine c’t in Hanover. Artificially extended traffic light phases could create traffic jams or cause chaos. Because almost all cities rely on technology that is 40 years old.
The meeting point is at a busy intersection in the north of Hanover. It is already dawn. We have an appointment with two IT experts. They want to show us how easy it is to manipulate traffic lights. You don’t need much for this: an antenna, a radio, a laptop – and off you go.
Green wave via radio signal? Possible due to a security gap, because in many cities in Northern Germany traffic light systems are still operated with analogue radio technology.
The car is still a good 50 meters away from the traffic light. She likes red. The IT professional presses the enter key on his laptop. The radio cuts out the hissing for a split second. It cracks. That’s the signal, the IT expert counts down: “Two – one”. The traffic light changes. One green wave at your own request, delivered by radio signal.
The IT experts approached us reporters from NDR, BR and c’t used to show how easy it is to manipulate traffic light systems. This is punishable by law, so they remain anonymous. They want to draw the public’s attention to the fact that this security gap exists: Although not all traffic lights at an intersection can be switched green or red at the same time, the traffic light phases are artificially extended, creating traffic jams or causing chaos, the experts explain. The IT experts use the same analog radio signal that is used by buses, for example, to get through traffic faster. The signal is not encrypted. The problem has been known for many years, the analogue radio technology dates back to the 1980s.
Many large cities use insecure analogue radio
Reporters from Panorama 3 and kontrovers, BR Recherche and the computer magazine c’t asked 13 larger cities in northern Germany which technology they use to control traffic lights and to give priority to buses and trains. The result: Almost everyone uses the old analog radio technology, which is unencrypted by default. In the north, only Hamburg has partially switched to digital radio, which can be encrypted. When asked, many cities admit that the system can be exploited. The possible effects are small, it is said, and it is also very expensive and prohibited. No city is aware that the signal was ever deliberately exploited.
AUDIO: Critical infrastructure: traffic lights are easy to manipulate (7 min)
Problem: Sluggish digitization
Finds it frightening how easy it is to manipulate traffic lights: Prof. Mathias Fischer, computer scientist and specialist for critical infrastructures.
Professor Mathias Fischer is an IT expert and specialist in critical infrastructures, he teaches at the University of Hamburg: “It’s frightening how easy it actually is to influence traffic lights,” he says of the research results. Analog radio is a “very old protocol that comes completely without security mechanisms”. Manipulating individual traffic lights is limited locally, but it shows how digitization is also lagging behind in the transport sector. There is a lack of money and qualified staff: “There is a lack of well-trained computer scientists everywhere who can handle digitization,” says Fischer.
Digital radio offers more protection
When asked whether they were aware that these systems could be exploited, the city of Hanover did not comment. However, new technologies are being researched, they say. These could then also send in encrypted form and would not be exploitable.
To secure traffic lights, there is the option of switching to encrypted digital radio. A copying of the radio signals is then no longer easily possible. The cities must have converted their traffic light technology by the end of 2028: analog radio can only be used until then.
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