Information Rules

Information Revelation and Privacy in Online Social Networks (The Facebook case)
Pre-proceedings version. ACM Workshop on Privacy in the Electronic Society (WPES), 2005

Ralph Gross
Data Privacy Laboratory School of Computer Science Carnegie Mellon University Pittsburgh, PA 15213

Alessandro Acquisti
H. John Heinz III School of Public Policy and Management Carnegie Mellon UniversityPittsburgh, PA 15213

rgross@cs.cmu.edu ABSTRACT
Participation in social networking sites has dramatically increased in recent years. Services such as Friendster, Tribe, or the Facebook allow millions of individuals to create online profiles and share personal information with vast networks of friends - and, often, unknown numbers of strangers. In this paper we study patterns of information revelationin online social networks and their privacy implications. We analyze the online behavior of more than 4,000 Carnegie Mellon University students who have joined a popular social networking site catered to colleges. We evaluate the amount of information they disclose and study their usage of the site’s privacy settings. We highlight potential attacks on various aspects of their privacy, and we showthat only a minimal percentage of users changes the highly permeable privacy preferences.

acquisti@andrew.cmu.edu
In recent years online social networking has moved from niche phenomenon to mass adoption. Although the concept dates back to the 1960s (with University of Illinois Plato computer-based education tool, see [16]), viral growth and commercial interest only arose well after theadvent of the Internet.1 The rapid increase in participation in very recent years has been accompanied by a progressive diversification and sophistication of purposes and usage patterns across a multitude of different sites. The Social Software Weblog2 now groups hundreds of social networking sites in nine categories, including business, common interests, dating, faceto-face facilitation, friends, pets,and photos. While boundaries are blurred, most online networking sites share a core of features: through the site an individual offers a “profile” - a representation of their sel[ves] (and, often, of their own social networks) - to others to peruse, with the intention of contacting or being contacted by others, to meet new friends or dates (Friendster,3 Orkut4 ), find new jobs (LinkedIn5 ), receiveor provide recommendations (Tribe6 ), and much more. It is not unusual for successful social networking sites to experience periods of viral growth with participation expanding at rates topping 20% a month. Liu and Maes estimate in [18] that “well over a million self-descriptive personal profiles are available across different web-based social networks” in the United States, and Leonard, already in2004, reported in [16] that world-wide “[s]even million people have accounts on Friendster. [...] Two million are registered to MySpace. A whopping 16 million are supposed to have registered on Tickle for a chance to take a personality test.” The success of these sites has attracted the attention of the media (e.g., [23], [3], [16], [4], [26]) and researchers. The latter have often built upon theexisting literature on social network theory (e.g., [20], [21], [11], [12], [32]) to discuss One of the first networking sites, SixDegrees.com, was launched in 1997 but shut down in 2000 after “struggling to find a purpose for [its] concept” [5]. 2 Http://www.socialsoftware.weblogsinc.com/ . 3 Http://www.friendster.com/ . 4 Http://www.orkut.com/ . 5 Http://www.linkedin.com/ . 6 Http://www.tribe.net/.
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Categories and Subject Descriptors
K.4.1 [Computer and Society]: Public Policy Issues— Privacy

General Terms
Human Factors

Keywords
Facebok, Online privacy, information revelation, social networking sites

1. EVOLUTION OF ONLINE NETWORKING

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