Monday, November 22, 2010

XSS track got ninja stealth skills thanks to HTML5

XSS-Track, a point of concept project on how to track users through XSS vulnerability today got even better: now it can change URL in browser address bar as you navigate through the site, making it even more transparent for the victim.

It is possible thanks to a HTML5 feature - window.history.pushState(). It was created for AJAX websites so that they could easily change window location bar and manipulate history. Read more about the it on WHATWG site.

It's a great and convenient feature for developers - for example, AJAX apps can now easily support back & forward buttons without resorting to URI fragment identifier (#) hacks. But it can also be used for malicious purposes. Basically, in HTML5 you can no longer trust the location bar. For security reasons, specs say you can only change a path (i.e. not hostname, port etc.) and of course it is subject to same-origin restrictions but that is enough for XSS-Track. So now we have these convenient functions in XSS-track source code:

var getPath = function(url) {
  return url.match(/(\/.*)/)[1];

var changeAddressBar = function(url) {
  try {
    // html5 goodness - should work in Safari, Chrome, FF 4
    window.history.pushState({}, "", getPath(url));
  } catch(e) {}

and navigating a link within vulnerable domain will update the address bar path accordingly, making XSS-track practically invisible (unless you click an external link).

window.history.pushState() works in Chrome 5, Safari 5 and Firefox 4 and more browsers will come in future. When it's not available, XSS-Track will just leave the URL of a vulnerable page, so we're forward compatible. Try and hack the demo site to see the effects in one of those browsers to see it in action. HTML5 FTW!


Anonymous said...


Krzysztof Kotowicz said...


Mhm, mario is THE guy when it comes to wicked XSS vectors & html5 security.

Anonymous said...

Oh good grief, that's nasty.

Certainly hope that the browsers will come up with a UI element that will warn when the URL is being changed by javascript, or show the actual URL on hover, or whatever.

Frank said...

Any updates for FF10+, Chrome 18+ etc. ??

kkotowicz said...

history.pushState() should work in both of them, it's widely supported now -

mole removal at home said...

Pretty good post. I just stumbled upon your blog and wanted to say that I have really enjoyed reading your blog posts.I recently came across your blog and have been reading along. I thought I would leave my first comment. I don’t know what to say except that I have enjoyed reading. Nice blog. I will keep visiting.