A Google security engineer discovered that jQuery Mobile can expose websites to cross-site scripting (XSS) attacks if an open redirect vulnerability is also present.
The jQuery Foundation’s jQuery Mobile project is an HTML5-based user interface system designed for developing responsive websites and web applications that can be accessed from any type of device. According to BuiltWith, jQuery Mobile is currently used on more than 150,000 active websites.
Google’s Eduardo Vela discovered a few months ago that jQuery Mobile checks the location.hash, which returns the anchor part of a URL. If there is a URL in the location.hash, it uses the history.pushState method on it and adds it to an XMLHttpRequest object. The response to this request is used with innerHTML.
The use of history.pushState should prevent XSS attacks, but exploitation is still possible if the website is affected by an open redirect vulnerability. An example provided by Vela looks like this:
http://jquery-mobile-xss.appspot.com/#/redirect?url=http://sirdarckcat.github.io/xss/img-src.html
There may be many websites vulnerable to such attacks considering that some organizations, including Google, don’t treat open redirects as vulnerabilities. Open redirects can be found on major websites such as Google, YouTube, Facebook, Baidu and Yahoo.
The expert reported his findings to jQuery Mobile developers, but the problem will not be addressed any time soon due to concerns that changing the current behavior could break existing applications. The jQuery team has admitted that developers should be warned about the risks.
“One opportunity for further research, if you have time in your hands is to try to find a way to make this bug work without the need of an Open Redirect. I tried to make it work, but it didn’t work out,” Vela wrote in a post on his personal blog.
“In my experience, Open Redirects are very common, and they are also a common source of bugs. Perhaps we should start fixing Open Redirects. Or perhaps we should be more consistent on not treating them as vulnerabilities. Either way, for as long as we have this disagreement in our industry, we at least get to enjoy some XSS bugs,” the researcher said.
Related: XSS Found in Silently Installed Acrobat Chrome Extension