Researchers reveal 'clickjacking' attack info

The long list of vulnerabilities involves browsers, Web sites and plug-ins like Flash

The security researchers who two weeks ago warned of new "clickjacking" vulnerabilities in browsers, Web sites and popular plug-ins, revealed a dozen variants of the bug yesterday.

And that's just for starters, said Robert Hansen, founder and CEO of SecTheory LLC. "The list doesn't cover all the other kinds of plug-ins that are vulnerable, or all the browsers or all the Web sites," Hansen said in an interview Wednesday. "The list got so long so fast that it was impossible to keep track of all the subissues."

On Tuesday, Hansen disclosed more information about so-called clickjacking, the new class of vulnerabilities that he and fellow researcher Jeremiah Grossman, the chief technology officer at WhiteHat Security Inc., first mentioned during a semiclosed presentation at a New York security conference on Sept. 24. Hansen and Grossman had originally intended to present the bulk of their findings then, but agreed to withhold most of the information at the request of Adobe Systems Inc., which said it would quickly patch its software against such attacks.

Early yesterday, however, Israeli researcher Guy Aharonovsky posted a proof-of-concept demonstration that uses clickjacking tactics to invisibly reset Adobe's Flash privacy settings and secretly turn on the computer's webcam and microphone for remote spying.

With the cat out of the bag, Adobe gave Hansen and Grossman the go-ahead to get specific about their findings. Hansen then posted a list of 12 different clickjacking scenarios on his blog.

"There are multiple variants of clickjacking," Hansen said in the post. "Some require cross domain access, some don't. Some overlay entire pages over a page, some use iframes to get you to click on one spot. Some require JavaScript, some don't. Some variants use CSRF to preload data in forms, some don't."

Of the dozen he spelled out, only two have been resolved. For example, Adobe has not patched Flash against one of the clickjacking vulnerabilities Hansen and Grossman reported to the company. However, yesterday, Adobe issued a security advisory with instructions on how to secure Flash against webcam and microphone hijacking in lieu of a patch.

"[Aharonovsky's] proof of concept was just a demonstration, but clickjacking can do all kinds of things," Hansen said today. "If you think about the traditional Web applications that have a 'Confirm' button or an 'Add a friend' button or any kind of single-button click, they're all going to be more vulnerable now."

But he also said there's no reason to panic; clickjacking wouldn't make the Internet a much more dangerous place in the short term. "If we assume that the majority of Web applications are vulnerable to some exploit, and they are, then clickjacking is making things worse, but it's already so bad that it doesn't really matter," Hansen said.

"We made it very clear that we didn't feel that this was the end of the Earth," he continued. "However, that doesn't lessen the ultimate severity of problems like monitoring people remotely with webcams or getting people to transfer money from their bank accounts."

Hansen remained convinced that the place to stymie clickjacking attacks for now is within the browser. "Absolutely. There are ways to patch your own site using 'frame-busting' code, but that doesn't work all the time, and you'd have to update every single page with sensitive information. But I don't think it's unrealistic to think that the browser makers could release a quick patch," he said.

Hansen and Grossman have been in contact with the security teams at Microsoft, Mozilla and Apple, which are responsible for Internet Explorer, Firefox and Safari, respectively. "I don't have any idea about their timelines," he acknowledged.

Even so, fixing browsers may be a shortsighted strategy in the long run. "Fixing each browser, as they get less and less alike, only adds a lot more complexity to the problem," Hansen said.

The trouble with that approach? "When Jeremiah and I were looking at clickjacking, we found all kinds of random browser bugs," said Hansen, describing the quantity as a "tons of bugs" and a "mess load" of flaws. "A lot of them were unrelated to clickjacking," he said. "But as other researchers start looking at clickjacking, they'll find their own interesting bugs."

Many will be, as Hansen and Grossman found, browser- or platform-specific. "As browsers get less and less alike, this [browser-specific bug finding] will get more and more common," he said. Adding more code to plug clickjacking holes, with each browser handling the problem its own way, will invariably open them to new, as-yet-undiscovered attacks, Hansen argued.

For the moment, there's little that end users can do to protect themselves and maintain the Internet's usability, said Hansen. One tactic, available only for Firefox users, is to install the NoScript add-on. "NoScript does a great job of supplementing [Mozilla's] slowness in patching, but it's not really the best way to protect users," Hansen said, referring to NoScript's content blocking, which can render some sites unusable.

"Finding a solution for clickjacking will be very complicated, which is why we don't see a quick solution," Hansen said. "But if we don't give it the attention it deserves now, it could be used in the future for much more effective targeted attacks."

Copyright © 2008 IDG Communications, Inc.

It’s time to break the ChatGPT habit
Shop Tech Products at Amazon