Securing a femtocell-based location service

Mobile device users are increasingly incented to falsify their locations to retain location privacy while capturing economic benefits such as location-based retail discounts. Location spoofing is easily achieved with several widely-used location services that rely on smartphone applications to convey GPS coordinates, IP addresses, or WiFi Positioning System radio environment data. In earlier work we introduced a network infrastructure-based system that provides spontaneous, rapid, and robust mobile device location authentication by supplementing existing 802.11x APs with off-the-shelf femtocells. The proposed system has the property of leveraging mobile operator infrastructure, without requiring operator participation in either providing or authenticating location. In this paper we present a security analysis of the location authentication system. We assess its resistance to DoS attacks, identify various approaches for a mobile user to deceive a location verifier with and without the assistance of a colluder, and explore the tradeoffs between cost and complexity in mounting such attacks. Finally, we identify a collection of system modifications and countermeasures to anticipated attacks designed to decrease location authentication system vulnerabilities and increase privacy protection.