Facebook

Yes, I know I've been gone for a while, but I was busy. My apologies. Now that I am back, I will update more frequently. Now down to the matter at hand.

I'm sure most, if not all of you use or are aware of Facebook. Just as a brief recap, Facebook is a social networking site that allows you to add friends, communicate with them, play games, blah, blah, blah. To explain the problem at hand, we need to discuss some features of Facebook. The first one is Groups. Now a Group is basically a group of people brought together by some common theme, such as this group about potatoes. What people soon did was make groups for celebrities, fictional characters, TV Shows, movies and so on and so forth. Facebook thought "Well, this can't be right!" Thus were born fan pages. Its essentially a group with limited functionality, such as no messaging to all members.

Now, when a friend becomes a fan of something you get a message in your newsfeed saying "Friend is now a fan of Something." With your friend's name as a hyperlink to their profile page and similarly the name of the page links to the page itself. Of course Facebook changed "Become a Fan" to "Like", thus making it "Friend now likes Something."

However Facebook did not stop there. No, that would be easy and the sensible thing to do. They then went and did possibly the worst thing possible. They allowed the fan page hyperlink to direct to you to an external website!!! So now you can click on a page and you would be whisked of Facebook and taken to some other website.

Now where's the problem you ask? Surely Facebook checks all of these sites and ensures that they are safe and all that jazz. Sadly not. A large number of sites exsist where simply visiting the site makes you Like it on Facebook and publishes that your friends newsfeed, who the click on the link and so a worm is born. This has a non-destructive payload, but it is definatly proof of concept.

What's even worse, in a reaction to exceptionally long page names, somebody posted a page on how to remove them from your newsfeed. This lead to site, which then issued a pop-up saying "I don't know either!" Really funny right? Yes, because these sites can actually execute arbitrary code and do essentially anything. The main concerns here are Clickjacking and Cross-Site-Scripting. These can be used to do well potentially anything to your system.

Ironically as I am writing this post, I have come across this blog post from Sophos' Graham Cluely. This shows that it is possible and it has been done. I will leave you to read that, as well, his post is probably better then mine will ever be.

Right, so having been a bit scared, what do we do? Simple:

DO NOT LIKE RANDOM PAGES!!!
DON'T DO IT!!!

Seriously, don't!