Project A4

Privacy Threats in Social Networks

Principal Investigators

Krishna Gummadi

Manuel Gomez Rodriguez

Project Summary

Any information posted by a user on social networking sites like Twitter and Facebook can spread or exploited in multiple ways. First, friends of the user who see the information can spread the information to others, who in turn can spread it to more users. Such information spreading can easily bring information to recipients it was not originally intended to, and can even set off large-scale social contagions or cascades of information both within and across users of different sites. Second, many sites offer mechanisms that can tremendously increase the exposure of information to a lot of users, such as proactively recommending such information to other users or allowing third-party advertisers to target users leveraging their personal data.
Unfortunately, users sharing information on social networking sites today lack a good understanding of how the different ways in which information spreads increase the exposure of their information. Not knowing which or when or how other users or advertisers will get to see an individual’s personal information makes the individual powerless in controlling exposure of her own information as well as her exposure to third-party ads, resulting in serious privacy loss. This problem manifests itself across a broad range of scenarios, from small-scale undesired spreading within user’s friends circles (e.g., the wrong picture reaching the classroom bully), all the way to worstcase scenario violations, recently highlighted by popular media, where ads related to job or housing opportunities, are predominantly shown to users belonging to certain demographic groups, resulting in a discriminatory use of personal information.
The central question we originally emphasized is: To what extent can we predict and control how widely, how quickly, and to whom a piece of private information will spread? However, since the proposal, the threat posed by third-party advertisers exploiting users’ personal data on social networks to discriminatorily deny opportunities for certain social groups exposure or to spread misinformation and stoke societal divisions has grown to such prominence that we decided to investigate our original objectives in the context of online targeted advertising.

Role Within the Collaborative Research Center