Privacy advocates have long warned people that social networks like Facebook collect users' personal data in order to target them with advertisements. A recent report by ProPublica has revealed that Facebook not only collects information that users post themselves, but also purchases other information about them from commercial data brokers. With this information, the company builds detailed data dossiers about each of its users.
Facebook vaguely mentions on its site that it collects information on its users “from a few different sources,” but doesn't mention that it collects financial data that users are not publicly sharing. Users are also barred from seeing the detailed information that the company has on them. “They are not being honest,” Jeffrey Chester, executive director of the Center for Digital Democracy, said. "Facebook is bundling a dozen different data companies to target an individual customer, and an individual should have access to that bundle as well.”
ProPublica tracked down a list of 29,000 categories that Facebook provides to ad buyers, around 600 of which were provided by third-party data brokers. These latter categories included financial information like income, value of “total liquid investible assets $1-$24,999,” and “individuals that are frequent transactors at lower cost department or dollar stores.”
Steve Satterfield, a manager of privacy and public policy for Facebook, said that the company's “approach to controls for third-party categories is somewhat different than our approach for Facebook-specific categories. This is because the data providers we work with generally make their categories available across many different ad platforms, not just on Facebook.”
Users can opt out of some advertising-based tracking via the site's ad preferences, but Satterfield explained that users who want to opt out of having their information shared by data brokers need to contact each data broker individually. This is no trivial task. For example, opting out of Oracle's Datalogix data service requires “sending a written request, along with a copy of government-issued identification” via postal mail.