New research from engineers at the University of California—San Diego (UCSD) suggest some unsettling findings about the mobile device you’re carrying in your pocket every day. Those Bluetooth signals your phone is constantly putting out into the ether? They’re about as unique as a fingerprint and highly trackable. That means a person’s movement and activity can be easily monitored. Researchers presented their findings at the IEEE Security and Privacy conference on May 24, 2022.
The idea that mobile phones have trackable features isn’t an inherently new concept; researchers have shown that WiFi and various other types of wireless tech, for example, have similar “fingerprint” properties that can make it easy to identify and track an individual’s location and movement. What UCSD researchers were able to show was that this is also happening with Bluetooth technologies, with a high degree of accuracy.
The problem highlighted by this new research is underscored by the fact that Bluetooth signals are given off constantly, making it easier to capture, trace, and track the origin of the signal. What’s more, researchers were able to identify what gave Bluetooth signals their unique “fingerprint” features that could allow someone to identify the device they came from. The manufacturing process for wireless devices usually causes accidental “imperfections” in the device’s Bluetooth hardware. These “mistakes” lead to unique changes in the Bluetooth signal the device generates that is specific to a device.
Researchers then conducted experiments to understand how these Bluetooth signals are traced. Techniques used to trace WiFi signals to a unique location often rely on a certain part of the signal that, in Bluetooth signals, is significantly shorter. As a result, many existing techniques are not helpful for tracking Bluetooth signals. Instead, researchers developed algorithms focused around hardware imperfections to locate a Bluetooth signal’s fingerprint, highlighting that Bluetooth signals can be highly traceable.
Bluetooth plays a crucial role in many tools we might take for granted, such as Apple’s “Find My” feature that allows users to find a misplaced iPhone or other Apple device. We also use Bluetooth to connect our phones to other smart devices, such as earphones or smart T.V.s. Some COVID-19 tracing apps also use Bluetooth.