How data brokers endanger privacy

In the last decades, the information trading industry experienced important growth with the advent of Big Data. Information traders such as data brokers keep more and more detailed profiles of individuals, thus storing a variety of sensitive information. Those practices raise public concern, as leakage of personal data can harm data subjects and put the individual at risk of frauds or identity thefts. Even more worrisome is the fact that some data brokers, namely person search sites, deliver important amounts of personal data for free, by providing person registries on their public website. While a single data broker doing so may cause limited harm, when multiple person search sites provide different kinds of easily accessible personal information, those data can be linked to produce a complete profile containing a wide range of sensitive information. To provide the readers with an understanding of the current data broker industry, we conducted a survey on 75 data brokers and present the results in this paper. Furthermore, to show how easy it is to link data across different data brokers, we developed a system that automatically collects and links profiles from different person search sites. This system, named DROPLET, requires limited human intervention, but can produce linked profiles containing large amounts of personal sensitive information.