In this paper, we explore the capabilities, the current
prevalence and technical limitations of this new tracking technique
based on three commercial tracking solutions.
To this
end, we develop detection approaches for ultrasonic beacons
and Android applications capable of processing these. Our
findings confirm our privacy concerns:
We spot ultrasonic
beacons in various web media content and detect signals in
4 of 35 stores in two European cities that are used for location
tracking.
While we do not find ultrasonic beacons in TV
streams from 7 countries, we spot 234 Android applications
that are constantly listening for ultrasonic beacons in the
background without the user’s knowledge.
