Identity Trail: Covert Surveillance Using DNS

The Domain Name System (DNS) is the only globally deployed Internet service that provides user-friendly naming for Internet hosts. It was originally designed to return the same answer to any given query regardless of who may have issued the query, and thus all data in the DNS is assumed to be public. Such an assumption potentially conflicts with the privacy policies of private Internet hosts, particularly the increasing numbers of laptops and PDAs used by mobile users as their primary computing device. IP addresses of such devices in the DNS reveal the host’s, and typically the user’s, dynamic geographic location to anyone that is interested without the host’s knowledge or explicit consent. This paper demonstrates, and measures the severity of an attack that allows anyone on the Internet to covertly monitor mobile devices to construct detailed user profiles including user identity, daily commute patterns, and travel itineraries. Users that wish to identify their private hosts using user-friendly names are locked into the DNS model, thus becoming unwitting victims to this attack; we identify a growing number of such dynamic DNS users (two million and climbing), and covertly trail over one hundred thousand of them. We report on a large scale study that demonstrates the feasibility and severity of such an attack in today’s Internet. We further propose short-term and long-term defenses for the attack.