A new Facebook worm is making the rounds today, with a brilliant landing page that has already caused many infections.When users visit the page the worm spreads from while logged onto Facebook, the worm automatically reposts itself on their Facebook Walls so their friends will see and click on it. The worm also copies your wall.

The worm's landing page is brilliant -- alluring yet mysterious, and very clean, just like we techies like it. You see a picture of a model in lingerie looking back at you over her shoulder. To the side of the picture there is the simple text: "Wanna C Somthin' HOT!??" and under it: "Click Da' Button, Baby!"

Nothing happens when you enter the page except for the malicious activity, although a friendly looking picture, looking like a button, is indeed there.

A friend, Nick Fitzgerald, helped me analyze how the worm works. He writes about it in his blog:

"This worm uses what is technically known as a CSRF (Cross-site Request Forgery, also called XSRF) attack. A sequence of iframes on the exploit page call a sequence of other pages and scripts, eventually resulting in a form submission to Facebook "as if" the victim had submitted a URL for a wall post and clicked on the "Share" button to confirm the post." As a personal lesson, I have to admit mea culpa. I saw the worm being posted from a friend's page and didn't believe it to be dangerous because the lure is pretty cool. So I reposted it without thinking and went to visit the page. Immediately a second post appeared, and after a moment's confusion, I removed them both.

This shows that even experts can become complacent and trust systems when they really shouldn't. It's a good reminder for me to be more careful with social networks, which for some reason I have grown used to trusting more, without even noticing it happen!

Even though it was only there for a few seconds, me posting the page to Facebook without checking first is by far more embarrassing than if I got infected. But this is how we learn. I share this moment of embarrassment with you so others will both learn from me. No matter who you are, these things can get you -- which is why being thoughtful online is a good idea.

Follow Gadi Evron on Twitter: http://twitter.com/gadievron

Gadi Evron is an independent security strategist based in Israel. Special to Dark Reading.