Ah. Good old noscript.

http://i.imgur.com/Cb17T.png

The trick is to overlay an element over the top of a link, with the CSS of "pointer-events: none;".

Clicking the div will click the underlying link, which will (if you're logged into facebook) "like" the Facebook Developer group.

Is this an issue with HTML5, or is it really an issue with how easy sites can manipulate your Facebook account?

Neither. The problem is that your browser handles click events on an invisible layer.

Well, no; there's two problems now. The first one is that your browser will handle click events on invisible and near-invisible layers. The second one is that your browser will allow click events to flow through opaque and near-opaque layers.

Those are not bugs, IMO.

A lot of web Javascript would be useless if events didn't bubble, and being able to define invisible click areas is useful in a variety of contexts.

Sucks that a few people are going to be malicious about it but I think the benefits outweigh the drawbacks.

The problem is not that events bubble, but that clicks fall through visible layers to lower ones and get caught invisible ones on top of what you intended to click on.

Invisible click areas as you called it are not the same as multi-layered click targets imho.

Yes, there is a different term for each case, but both boils down to "if I can't see it, why would I click it".

I hope this doesn't mean the end of niche browsers, or at least not those built on well-known rendering engines like WebKit.

This is just another brick in the wall. The web is /not/ a platform that's friendly to new implementations, and it never will be; the complexity that's constantly being added ensures this. It also means we're all going to have a lot fewer guarantees of anything like sane behavior when using the web in the years to come.

Even without this trick it's trivial to clickjack a like button - just place the button on a div with an alpha transparency of 0.01 and trick the user in to clicking it.

Unfortunately it simply isn't possible to provide something like the Like button without being vulnerable to click jacking. I assume Facebook decided that the benefits outweighed the drawbacks. There's probably something clever they can do on the server side to statistically detect and penalize likely clickjacking attempts.

They do, eventually (unsure of the criteria) it will start showing a second confirmation dialog if they detect something untoward which you have to confirm your like with, although click jacking that too might also be possible.

You don't need CSS4 to clickjack, just put the Facebook Like button on top of the link and apply opacity: 0.

http://jsfiddle.net/txbYs/

The problem is that this new directive makes this exploit first-class citizen.

That's not a problem at all. If it's worth it to do it, people will do it even if it takes 200 lines. If it's not, they won't bother. So, even with it being achievable as a "first-class" option in CSS4, I don't see any particular rise of this exploit happening.

It's like arguing that something is safer because it requires 10 lines of code instead of one to do the exploit. That's security by obscurity.

I guess you're right. Maybe the effect is reverse even - by raising attention to potentional pitfalls.

Still, I can not think of a possible use case this can be useful. Maybe other options will make it worth knowing about.

Looks like the same game as the "don't click" twitter button (that everyone clicked anyway) from 2009. That was iframes/css.

http://shiflett.org/blog/2009/feb/twitter-dont-click-exploit

It prompted me to log in even though I have FB open and am logged in in a separate tab.

I tried it and I did not have any prompt. I liked the Facebook Developers page without seeing any prompt or confirmation so it was completely transparent.

Maybe our privacy settings are different and that's why you saw a prompt even though you were logged in.

I've used pointer events ages ago - surprised it's part of CSS4… (the nav bar on http://www.splashdisplay.co.uk/ uses it so the nav can be behind the curve)

I don't see how this is any different XHTML or HTML 4... what am I missing?

I updated the title, it should have been CSS4 since that's where it's being defined.

I know people who used tricks like this and some clickjacking on the share button to get 1 million+ person fan pages. Many of them were seized, but for a while it was easy.

I run Facebook Disconnect and it makes the web much nicer, this demo is non-functional with it.

That's not really the point. I mean, not having a Facebook account stops this demo too. There are other things you might not want to be tricked into clicking on.

This has likely been happening quite some time, especially on file locker sites.

CSS4? Where was I? and When??

They make a new version every time there's been enough changes...