One prominent downside to the tremendous user base that social networking sites amass is that they become huge targets for malicious intents. Given the sheer size of many of these sites, protecting users from online attacks isn't terribly practical, so it's usually left up to the individual. Facebook has been dealing with this first hand lately, after coming under attack by a large number of phishers.
In the past few days, Facebook has reported a massive surge in phishers using fake pages and other viral methods to trick users into releasing usernames and passwords. This expands further with the stolen information being used to harvest more usernames via contact lists. With a user base of 200 million, even a small percentage of infections could spiral out of control if this isn't dealt with. Declining to reveal specific numbers, Ryan McGeehan, threat analyst for Facebook, admitted that it was enough for them to begin taking steps to stop the attacks.
Attacks like these come and go, and McGeehan along with many security experts believe that the number one way to protect any group of people is through education. But when you are dealing with literally hundreds of millions of people, where do you start and how do you educate them all?