On the privacy of real-world friend-finder services

Privacy protection in the deployment of location based services is a hot topic both in CS research and in the development of mobile applications. In this paper we consider a location based service that currently has hundreds of millions of users and we show how we developed a software that is able to discover their exact positions, by only using information publicly disclosed by the service. Our software does not exploit a specific limitation of the considered service. Rather this contribution shows that there is an entire class of services that is subject to the attack we present.