SNKnock: A free security tool for Facebook users
  The Facebook Social network is very famous and widely used by millions of users all over the world. Facebook comes with high level of usability so users can easily find their friends and connect to them, but there are security issues related to this process where the attacker can make same-site or cross-site profile cloning attacks to get other users data. In this paper we will identify advanced same-site or cross-site profile cloning attacks then we will propose a security solution to these attacks where the user must record a voice message and answer some questions when he sends a friend request to another user, and then the other user will listen to this message before deciding to accept or reject the request. We implemented this solution by developing new web application called SNKnock which is available as free service. 
Mahmoud Samir Fayed
cs.CR