The vulnerabilities when design or implement the
security mechanisms adopted by facebook. For
example, research conducted by J. Bonneau has shown that
search engines such as Google have the ability to acquire a part
of social graph among users without logging to facebook
[12]. Furthermore, the unencrypted data at the transport layer
may lead to FITM attack[13]. In addition, the vulnerabilities of
facebook query language (FQL) may bring about the leak of
social graph among users too[14]. Moreover, the attack named
iCloner, which clones user data between different online social
network sites, will create false user accounts and then send out
friend requests to other normal users to extend the social
groups for these false user accounts[15].