DeTagTive: Linking MACs to Protect Against Malicious BLE Trackers

Abstract

Bluetooth Low Energy (BLE) location trackers are popular and useful for finding misplaced keys, devices, and other items. However, they can also be used to track people and enable abuse. The companies that make location trackers, such as Apple, have worked to address these issues by adding notifications within their ecosystem and publishing recommendations for other manufacturers, creating a vertically integrated solution. More generally, however, BLE devices which rotate their MAC addresses remain elusive to responsible detection within and across many manufacturer platforms. Rotation of MAC addresses is crucial in some non-malicious usage scenarios for the privacy of the device owner, but this feature also makes detection more difficult. In this work, we propose and evaluate a detection algorithm that is robust to rotating MAC addresses by using parameters that appear to offer implicit continuity, including signal strength and advertisement intervals. A preliminary test of our algorithm, on four common BLE trackers and across multiple scenarios, shows this approach to be promising and practical.