Yes, Virginia, There Is a Facebook Virus

This is to confirm that some email alerts currently going around warning of malware attacks on Facebook members via the network's internal message service are true. The attacks are particularly insidious because the potentially destructive messages appear to come from friends.

The culprit is an Internet worm known as Koobface (get it?). The main thing you need to know to protect yourself is this: The worm is unleashed by clicking on a link in a Facebook message -- usually something on the order of "You look funny in this new video," "My friend catched you on hidden cam," or "Secret Video by Tom," etc. -- which causes a fake dialogue box to appear instructing the user to download the latest version of Flash Player. If the user complies, a Trojan horse is downloaded to their computer.

Don't click on questionable-seeming links.

Facebook advises members who believe they've inadvertently downloaded the malware to run a virus scan and reset their passwords.

Read more: Destructive Koobface Virus Turns up on Facebook

See also: Antivirus @ About.com