Multiple identity, or Sybil attacks pose a fundamental problem in OSNs. In a Sybil attack, a malicious user creates multiple (Sybil) identities and takes advantage of the combined privileges associated with these identities to abuse the system by spamming, rating manipulation etc. Recently, there has been significant research interest in leveraging social networks to defend against Sybils. While much of this work may appear similar at first glance, our research pointed out that, existing social network-based Sybil defense schemes can be divided into two categories: Sybil detection and Sybil tolerance. We characterize these two types of systems; they both leverage global properties of the underlying social graph, but they rely on different assumptions and provide different guarantees: Sybil detection schemes are application-independent and rely only on the graph structure to identify Sybil identities, while Sybil tolerance schemes rely on application-specific information and leverage the graph structure and transaction history to bound the leverage an attacker can gain from using multiple identities. We build Sybil tolerant systems to defend against email spammers, frauds in online markets and large scale crawlers in Online social networks.

 

Defending against large-scale crawls in online social networks
Mainack Mondal, Bimal Viswanath, Allen Clement, Peter Druschel, Krishna P. Gummadi, Alan Mislove and Ansley Post. ACM International Conference on emerging Networking EXperiments and Technologies (ACM CONEXT), December 2012.

Canal: Scaling social network-based Sybil tolerance schemes
Bimal Viswanath, Mainack Mondal, Krishna P. Gummadi, Alan Mislove, and Ansley Post. European Conference on Computer Systems (EuroSys), Bern, Switzerland, April 2012.

Exploring the design space of social network-based Sybil defenses
Bimal Viswanath, Mainack Mondal, Allen Clement, Peter Druschel, Krishna P. Gummadi, Alan Mislove, and Ansley Post. International Conference on Communication Systems and Networks (COMSNETS), invited paper, Bangalore, India, January 2012.

Bazaar: Strengthening user reputations in online marketplaces
Ansley Post, Vijit Shah, and Alan Mislove. Symposium on Networked Systems Design and Implementation (NSDI), Boston, MA, March 2011.

An Analysis of Social Network-based Sybil Defenses
Bimal Viswanath, Ansley Post, Krishna P. Gummadi, and Alan Mislove. ACM SIGCOMM 2010 (SIGCOMM), New Delhi, India, August 2010.

Ostra: Leveraging trust to thwart unwanted communication
Alan Mislove, Ansley Post, Krishna P.Gummadi, Peter Druschel. Conference of Networked Systems Design and Implementation (NSDI), San Francisco, CA, April 2008.

 

Bimal Viswanath
Mainack Mondal
Ansley Post
Allen Clement
Peter Druschel
Krishna Gummadi
Alan Mislove