Can Bluetooth Track Your Phone and YOU?

Can Bluetooth Track Your Phone and YOU?

by Digitalknowledge in Knowledgebase on June 10, 2022

Can Bluetooth Track Your Phone and YOU? A team of engineers from the University of California, San Diego has demonstrated for the first time that the Bluetooth signals constantly emitted by our mobile phones have a unique fingerprint that can be used to track the movements of individuals.

Mobile devices, such as smartphones, smartwatches, and fitness trackers, transmit Bluetooth beacon signals at a rate of approximately 500 beacons per minute. These beacons enable features such as Apple’s “Find My” lost device tracking service, COVID-19 tracing applications, and the connection of wireless earbuds to smartphones.

Previous research has demonstrated the existence of wireless fingerprinting in WiFi and other wireless technologies. The crucial realization of the UC San Diego team was that this type of tracking can also be accomplished with Bluetooth and with high precision.

Nishant Bhaskar, a Ph.D. student in the UC San Diego Department of Computer Science and Engineering and one of the paper’s lead authors, said, “This is significant because in today’s world Bluetooth poses a greater threat because it is a frequent and constant wireless signal emitted from all our personal mobile devices.”

Researchers from the Departments of Computer Science and Engineering and Electrical and Computer Engineering presented their findings at the IEEE Security & Privacy conference on May 24, 2022 in Oakland, California.

Small manufacturing defects in the hardware of all wireless devices are unique to each device. These fingerprints result from the manufacturing process. These Bluetooth hardware flaws produce unique distortions that can be used as a fingerprint to identify a specific device. This would allow an attacker to circumvent Bluetooth anti-tracking techniques such as a mobile device’s constantly changing Internet connection address.

Bluetooth tracking of individual devices is not straightforward. Prior WiFi fingerprinting techniques relied on the fact that WiFi signals contain a lengthy known sequence, known as the preamble. However, Bluetooth beacon signal preambles are extremely brief.

Hadi Givehchian, a Ph.D. student in computer science at UC San Diego and the paper’s lead author, said, “The short duration produces an inaccurate fingerprint, rendering prior techniques useless for Bluetooth tracking.”

Instead of relying on the preamble, the researchers developed a new method that examines the entire Bluetooth signal. They developed an algorithm for estimating two distinct Bluetooth signal values. These values vary based on Bluetooth hardware defects, giving researchers a unique fingerprint of the device.

Real-world research

Using a variety of real-world tests, the researchers evaluated their tracking technique. 40 percent of 162 mobile devices observed in public areas, such as coffee shops, were uniquely identifiable, according to the first experiment. Next, they expanded the experiment by observing 647 mobile devices for two days in a public hallway. The team discovered that 47% of these devices contained unique fingerprints. Finally, the researchers demonstrated an actual tracking attack by fingerprinting and following a study participant’s mobile device as they entered their residence.


Although their discovery is unsettling, the researchers also uncovered a number of obstacles an attacker will face in practice. Temperature variations, for instance, can alter the Bluetooth fingerprint. Certain devices transmit Bluetooth signals with varying levels of strength, which impacts the distance at which they can be tracked.

Researchers also note that their technique requires a high level of expertise, so it is unlikely to pose a significant threat to the public at this time.

Despite the obstacles, the researchers determined that Bluetooth tracking is likely feasible for a vast array of devices. It also does not require sophisticated equipment; the attack can be carried out with less than $200 worth of equipment.

Options and subsequent steps

So how can the issue be resolved? Bluetooth hardware would need to be fundamentally redesigned and replaced. However, the researchers believe that simpler alternatives exist. The team is currently working on a method to conceal Bluetooth fingerprints using digital signal processing in the firmware of Bluetooth devices.

Additionally, researchers are investigating whether their method could be applied to other types of devices. Dinesh Bharadia, a professor in the Department of Electrical and Computer Engineering at UC San Diego and one of the paper’s senior authors, stated, “Today, every form of communication is wireless and vulnerable.” We are developing hardware-level defenses against potential attacks.

Researchers discovered that disabling Bluetooth may not prevent all mobile devices from transmitting Bluetooth beacons. Some Apple devices continue to emit beacons even when Bluetooth is disabled via the control center on the home screen. “As far as we know, the only way to completely disable Bluetooth beacons is to turn off your phone,” said Bhaskar.

Researchers are careful to note that although they are able to track individual devices, they cannot obtain information about the owners of those devices. The campus’ Internal Review Board and campus counsel reviewed the study.

Aaron Schulman, a computer science professor at UC San Diego and one of the paper’s senior authors, stated, “It’s the devices themselves that are being scrutinized.”

Physical-Layer BLE Location Tracking Attacks on Mobile Devices: An Evaluation

Dinesh Bharadia, Department of Electrical and Computer Engineering, UC San Diego

Nishant Bhaskar, Hadi Givehchian, and Aaron Schulman, Computer Science and Engineering Department, UC San Diego

Christian Dameff, Department of Emergency Medicine, UC San Diego

Eliana Rodriguez Herrera Hector Rodrigo Lopez Soto, UC San Diego ENLACE Program

Story Source:

Materials provided by University of California – San Diego.

Categories: Knowledgebase

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