How Anybody Can Measure Your Computer's Wi-Fi Fingerprint

Wireless Internet access has become one of the enabling technologies of the modern world.

Indeed, many think of Wi-Fi is the oxygen of the computer generation. While wireless access is hugely useful, it is also a security threat. Anybody can access a wireless network by masquerading as a computer that already has access.

Christoph Neumann and pals at the Technicolor Security and Content Protection Labs in Rennes, France, say they’ve developed a way of uniquely identifying a computer by the way it accesses Wi-Fi resources. They point out that characteristics such as transmission rates and frame inter-arrival time, depend on the Wi-Fi card a computer uses as well as the drivers and the applications involved. The large number of permutations of these ensures that most computers have a “Wi-Fi fingerprint” that uniquely identifies them. And that could help distinguish an authorized user from a malicious one.

Neumann and co begin their work by analyzing all the wireless traffic broadcast on a particular Wi-Fi channel in a number of different environments. They then analyzed the training data set looking for the characteristics of the devices involved. Finally, they use these parameters to see if they can uniquely identify machines in the validation datasets.

And the results are pretty good. They say that in ordinary conditions such as their office network, they uniquely identify machines with an accuracy of up to 95 percent. It’s a low-cost and passive technique that is difficult for malicious users to detect.