Yet Another Identity Stealing Bug. Will Creeping Normalcy be the Result?

June 1, 2010 at 9:38 am 2 comments

Elie Bursztein points me to a “Cross Site URL Hijacking” attack which, among other things, allows a website to identify a visitor instantly (if they are using Firefox) by finding their Google and possibly Facebook IDs. Here is a live demo and here’s a paper.

For the security geeks, the attack works by exploiting a Firefox bug that allows a page in the attacker domain to infer URLs of pages in the target domain. If a page like redirects to[username] (which is quite common), the attacker can learn the username by requesting the page in a script tag.

Let us put this attack in context. Stealing the identity of a web visitor should be familiar to readers of this blog. I’ve recently written about doing this via history stealing, then a bug in Google spreadsheets, and now we have this. While the spreadsheets bug was fixed, the history stealing vulnerability remains in most browsers. Will new bugs be found faster than existing ones getting fixed? The answer is probably yes.

Something that is of much more concern in the long run is Facebook’s instant personalization, which is basically like identity stealing, except it is a feature rather than a bug. Currently Facebook identities are available without user consent to only 3 partners (Yelp, Pandora and but there will be inevitable competitive pressures both for Facebook to open this up to more websites as well as for other identity providers to offer a similar service.

Legitimate methods and hacks based on bugs are not entirely distinct. Two XSS attacks on were found in quick succession either of which could have been exploited by a third (fourth?) party for identity stealing. Instant personalization (and similar attempts at an “identity layer”) greatly increase the chance of bugs that leak your identity to every website, authorized or not.

As identity-stealing bugs as well as identity-sharing features proliferate, the result is going to be creeping normalcy — users will get slowly inured to the idea that any website they visit might have their identity. And that will be a profound change for the way the web works. Of course, savvy users will know how to turn off the various tracking mechanisms, but most people will be left in the lurch.

We are still at the early stages of this shift. It is clear that it will have both good and ill effects. For example, people are much more civil when interacting under their real-life identity. For this reason, there is quite a clamor for identity. For instance, see News Sites Rethink Anonymous Online Comments and The Forces Align Against Anonymity. But like every change, this one is going to be hard to get used to.

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Facebook, Privacy, Public Opinion and Pitchforks Conferences: The Good, the Bad and the Ugly aspects

2 Comments Add your own

  • […] I won’t discuss to much this figure as it is already done in this paper.  For me the two important  point regarding  the evolution of web security showed by this figure is that nowadays web security is even more difficult than before. Back in 2005, web security was only about testing few vectors of attacks, mainly XSS and SQL injection. In 2010, the situation is way more complex, as the number of attack vectors exploded. For instance how many of you heard of the new attack released in May named  “Cross Site URL Hijacking“  ? In a nutshell this attack allows an attacker to know the URL parameters of a different origin by abusing the Firefox error object. While this attack might seems innocuous, it has serious privacy implications. […]

  • […] of leaking your identity to other parties. In my ubercookies series, I documented a series of bugs that can be exploited by an arbitrary website to learn the visitor’s identity. All of these […]


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I'm an assistant professor of computer science at Princeton. I research (and teach) information privacy and security, and moonlight in technology policy.

This is a blog about my research on breaking data anonymization, and more broadly about information privacy, law and policy.

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