WiFi networks could pose significant privacy risks even to people who aren’t carrying or using WiFi-enabled devices, say researchers at the Karlsruhe Institute of Technology (KIT) in Germany. According to their analysis, the current version of the technology passively records information that is detailed enough to identify individuals moving through networks, prompting them to call for protective measures in the next iteration of WiFi standards.
Although wireless networks are ubiquitous and highly useful, they come with certain privacy and security risks. One such risk stems from a phenomenon known as WiFi sensing, which the researchers at KIT’s Institute of Information Security and Dependability (KASTEL) define as “the inference of information about the networks’ environment from its signal propagation characteristics”.
“As signals propagate through matter, they interfere with it – they are either transmitted, reflected, absorbed, polarized, diffracted, scattered, or refracted,” they write in their study, which is published in the Proceedings of the 2025 ACM SIGSAC Conference on Computer and Communications Security (CCS ’25). “By comparing an expected signal with a received signal, the interference can be estimated and used for error correction of the received data.”
An under-appreciated consequence, they continue, is that this estimation contains information about any humans who may have unwittingly been in the signal’s path. By carefully analysing the signal’s interference with the environment, they say, “certain aspects of the environment can be inferred” – including whether humans are present, what they are doing and even who they are.
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