‘This technology turns every router into a potential means of surveillance’: Researchers warn you can be tracked and identified from Wi-Fi signals

Researchers have identified a new Wi-Fi router security threat
People in a room can be tracked using beamforming signals
No physical access to the router is required to utilize its radio waves

Researchers from the Karlsruhe Institute of Technology in Germany have demonstrated how everyday Wi-Fi routers can be hacked and used as surveillance tools, using only the radio waves that travel from and back to the router.

Here’s how it works: routers using Wi-Fi 5 or later have feedback signals sent back to them from connected devices, known as Beamforming Feedback Information (BFI). The router uses this feedback to control speeds and stability, but these messages are free-flowing through the air and can also be picked up by other devices.

If someone physically passes these signals, they are disrupted. The signal map isn’t quite like a 3D map of a room, but the way the signals change can act as a kind of signature for a person, based on how they walk and move through the room.

Surveillance hazard

Wi-Fi card

The researchers set up listening points around a path that the participants walked down (Image credit: Karlsruhe Institute of Technology)

The researchers ran tests with 197 volunteers and were able to identify people with 99.5% accuracy – as in they could say ‘person A walked by at this time and this time’. To actually connect people with their name and other details, some other data is required, such as a ping from a phone previously linked to the individual.

So a listening device could be hidden in an office and a hacker could tell who was at work that day, provided they knew which gaits matched which people. Once the first match is made, targets don’t even need to carry a device (such as a phone).

“This technology makes every router a potential means of surveillance,” says Julian Todt, one of the researchers. “If you regularly pass by a cafe that operates a Wi-Fi network, you can be identified there without noticing and be recognized later – for example by government authorities or companies.”

The research team wants to see more protection of BFI data in future Wi-Fi standards – otherwise this is potentially a very real security threat affecting most modern routers. You can read the entire research report here.

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