What a cute name for such a malicious thing. Actually koob is book spelled backwards, making the name koobface an anagram for the word facebook. Cute name or not, you don't want to get infected by this little virus.
How It Starts
It all starts out, innocently enough, with you getting a message from your friend (a fake message by the way) directing you to go watch a video on YouTube, or view a photo. Clicking on the link takes you to a site that tells you that you need to update your software (this is your first hint that something is not right).
Everything looks right though. Looks like your friend's Facebook photo at the top of the page, doesn't it (or does it). So you install the update, you want to see the video of your friend after all, can't see it without the download.
Now you have it, the Koobface Virus, and all because your friend (or was it your friend) wanted you to see a video. It wasn't really your friend by the way, it was the notorious Koobface virus in disguise.
The Koobface virus is all alone on your computer now and has free rein. Now he goes into your Facebook profile and starts sending messages and wall postings to all your Facebook friends, unbeknownst to you. What message is he sending? He's telling all your friends that you have a video that you want them to watch. It starts all over again.
Who It Affects
Obviously it's going to affect Facebook users. It's also been seen hanging out at Friendster, MySpace, Bebo, Tagged and LiveJournal. This leaves me to believe that many social networks are vulnerable.
How To Protect Yourself
One: Use antivirus software.
Two: Don't update software from a third party site. If you think you need to update your browser, go to your browser's website and update it from there.
Three: You don't need to update your software to see videos on YouTube or to view a photo, you just don't, period.