You unlocked the Mt. Everest badge on foursquare! Countering location fraud in Geosocial Networks

GeoSocial Networks (GSNs) are online social networks centered on the location information of their users. Users “check-in” their location and use it to acquire location-based special status (e.g., badges, mayorships) and receive venue dependent rewards. The strategy of rewarding user participation however makes cheating a profitable behavior. In this paper we introduce XACT, a suite of venue-oriented secure location verification mechanisms that enable venues and GSN providers to certify the locations claimed by users. We prove that XACT is correct, secure and easy to use. We validate the need for secure location verification mechanisms by collecting and analyzing data from the most popular GSNs today: 780,000 Foursquare users and 143,000 Gowalla users. Through a proof-of-concept implementation on a Revision C4 BeagleBoard embedded system we show that XACT is easy to deploy and economically viable. We analytically and empirically prove that XACT detects location cheating attacks.