Don't install fake Facebook Antivirus
Alas, another day, another Facebook security alert.
As soon as you install this malware, it will tag every single one of your friends in a photo in batches of about 20. It then posts that photo to your wall.
This is what the photo looks like:

If a Friend looking through the photos then clicks on the app’s link, they’ll see this:

If you have a lot of friends, you might end up with a series of albums like this:
Apart from the wall spamming, another obvious indication that this is a virus itself, is the url:
http://apps.facebook.com/kxetyegpgkxdwfy/
A valid application is not going to have a url with a bunch of jumbled letters at the end.
If you have been tagged in the photo by one of your friends (remember, they did not really do this – the app did automatically), you can remove the tag.
1. Open your photos
2. Click the offending picture
3. Look for your name in the list of people tagged
4. Click the ‘Remove Tag’ link that appears beside your name
The photo will then automatically be removed from your photo list.
Source:
http://www.f-secure.com/weblog/archives/00001920.html
http://thefacebookinsider.com/2010/03/warning-facebook-antivirus-will-virally-spam-your-friends/
