Security and Privacy Analysis of Tile's Location Tracking Protocol

We conduct the first comprehensive security analysis of Tile, the second most popular crowd-sourced location-tracking service behind Apple's AirTags. We identify several exploitable vulnerabilities and design flaws, disproving many of the platform's claimed security and privacy guarantees: Tile's servers can persistently learn the location of all users and tags, unprivileged adversaries can track users through Bluetooth advertisements emitted by Tile's devices, and Tile's anti-theft mode is easily subverted. Despite its wide deployment -- millions of users, devices, and purpose-built hardware tags -- Tile provides no formal description of its protocol or threat model. Worse, Tile intentionally weakens its antistalking features to support an antitheft use-case and relies on a novel "accountability" mechanism to punish those abusing the system to stalk victims. We examine Tile's accountability mechanism, a unique feature of independent interest; no other provider attempts to guarantee accountability. While an ideal accountability mechanism may disincentivize abuse in crowd-sourced location tracking protocols, we show that Tile's implementation is subvertible and introduces new exploitable vulnerabilities. We conclude with a discussion on the need for new, formal definitions of accountability in this setting.