Clickjacking, in which an attacker slips a malicious link or malware onto a legitimate Web page that appears to contain normal content, is an emerging threat experts have been warning about. The attack on Facebook was in the form of a comment on a user's account with a photo that lured the victim to click on it. The embedded link took the victim to a Web page that presented like a CAPTCHA or Turing test, and asked the user to click on a blue "Share" button on the Facebook page.
Once clicked, the victim is redirected to a YouTube video, and then the same post shows up on the victim's account and thus tries to infect his or her friends. Security experts say the attack appeared to be more of a prank or trial balloon, and it affects only Firefox and Chrome browsers, according to security expert Krzysztof Kotowicz, who blogged about the attack this week.
Facebook has now blocked the URL to the malicious site, fb.59.to. "This problem isn't specific to Facebook, but we're always working to improve our systems and are building additional protections against this type of behavior. We've blocked the URL associated with this site, and we're cleaning up the relatively few cases where it was posted -- something email providers, for example, can't do," a Facebook spokesperson says.
Robert "RSnake" Hansen, CEO of SecTheory -- who, along with Jeremiah Grossman, CTO of WhiteHat Security, warned the industry about the threat of clickjacking more than a year ago -- says Facebook and most other sites don't employ much anti-clickjacking protection.
"This could be the beginning of a new wave of anti-Facebook clickjacking worms," Hansen says. "This same concept has already hit Twitter several times. It generally takes a few attacks for companies like this to wake up and realize the problem doesn't magically go away just by blocking one link."
But Facebook's spokesperson says the social networking site is also "working against these attacks on a number of fronts," including deframing scripts and X-Frame options. Hansen recommends employing both of these methods to combat clickjacking.
The clickjacking concept is really nothing new, but Hansen and Grossman last year discovered a brand of clickjacking that spans browser families and doesn't even require a user to click on anything. Just loading a compromised page sets off the attack, and clicking on that page will likely make things worse for the victim, they say. Clickjacking is both a Web and a browser problem, but the fixes likely need to come from the browser vendors. But a fix goes to the way browsers work, which means there's no simple fix.
"Clickjacking is such an easy attack and one that is completely unaddressed. We'll see much more of this, especially across the social networks," WhiteHat's Grossman says.
Kotowicz blogged that the clickjacking attack contains malicious iFrames, and that the reason the attack didn't affect Internet Explorer and Opera is due to an incorrect HTML in one of the pages.
Meanwhile, Facebook is reminding users to be wary of any posts, messages, or links on Facebook or anywhere else that appear suspicious, the Facebook spokesperson says.
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