Hunter: Tracing anycast communications to uncover cross-border personal data transfers

Abstract

Cross-border personal data transfers are heavily regulated worldwide, with data protection authorities imposing huge fines on organizations that fail to meet their strict compliance requirements. However, network-level optimizations such as anycast addresses were not designed with personal data in mind, and their use may unwittingly divert personal data out of a legal boundary. This paper describes Hunter, an automated method to trace anycast communications and identify those threatening data protection compliance. We have applied Hunter in the wild to a set of Android apps to discover that all apps observed sending personal data to anycast addresses eventually carry out international transfers but fail to disclose them in their privacy policies. Our findings suggest that using anycast addresses to transmit personal data generally results in data protection compliance issues.