We have evaluated how vulnerable online social networks are to a large-scale infiltration by a socialbot network. We used Facebook as a representative online social network, and found that using bots that mimic real users is effective in infiltrating Facebook on a large scale, especially when the users and the bots share mutual connections.
Moreover, such socialbots make it difficult for online social network security defenses, such as the Facebook Immune System, to detect or stop a socialbot network as it operates. Unfortunately, this has resulted in alarming privacy breaches and serious implications on other socially-informed software systems. We believe that large-scale infiltration in online social networks is only one of many future cyber threats, and defending against such threats is the first step towards maintaining a safer social web for millions of active web users.