Having spent a lot of time on Facebook over the last few days I have noticed a growing number of appearances of Fan Check in my ‘Highlights’ section. I was intrigued to see what this was and why so many of my friends had been tagged.

Fan Check is a Facebook app that claims to be able to calculate your top fans by who has visited your profile. The app then creates an image with your top 20 friends in and tags them. This image then appears in the ‘Highlights’ section of friends you have in common to advertise the app.

It all sounds straightforward and like another vanity checking feature of Facebook. However, anyone who knows even the slightest thing about Facebook’s privacy policies will know that this app is seriously flawed. There is no way for a 3^rd party app such as Fan Check to know who has been looking at your profile. There would be a massive uproar if Facebook gave access to such data. So how do apps like Fan Check get the data? They simply compile a list of 20 of your friends.

The viral nature of such apps is huge, but what do the developers gain? Well there has been lots of speculation that the app is infact a virus. The virus supposedly acts by displaying the following message when you click on the app (located at apps.facebook.com/fancheck).

“FanCheck is adding new features and new capacity. This could take a few days.
Please become a fan, and we’ll send you an update when we’re back online”

The claim is that when you click to become a fan your Facebook account becomes ‘infected’. However, this is highly unlikely and nothing has been reported to security sites such as Symantic or McAffe. A Facebook app it’s self cannot do any damage to your computer (as long as you don’t click out from it to malware sites).

The second stage of the problem this is that spammers have jumped on the back of the fear and a vast number of malware sites. A Google search for “facebook fan check virus” will return a vast number of these malware sites.

The message is simple, if a Facebook app claims to be able tell you who has been viewing your profile is a scam and should be avoided. Also don’t search for “facebook fan check virus” and visit the results.

UPDATE: 09/09/09

The app has now been updated and the message has been changed to

“This application ranks your friends based on how often they interact with your Facebook wall. Interactions counted include wall posts, comments, likes, gifts and other public items posted to your wall. In accordance with the Facebook Privacy Policy, we do NOT count page views or private messages.”

The option to become a fan has also been removed