New phishing trick, data: URLs to avoid forgery reporting

This is a technical post about a new and interesting phishing technique seen today. Regular FastMail users can skip this post.

We saw an interesting new phishing attempt today that uses a relatively novel technique to try and hide the source of the attack and avoid it being reported as a web forgery.

Firstly the email itself looks reasonably well done (apart from the year in the subject being completely wrong), certainly it’s not the poor quality you often see. It looked like this (ANZ is an Australian bank):


Secondly, the email was sent using a compromised gmail account with a .edu address. In fact there were two separate emails, both from different compromised gmail .edu accounts. I imagine compromised gmail .edu accounts aren’t that easy to get, and this significantly reduced the chances of it being caught by any spam filter.

Thirdly, the phishing page itself is interesting in that it:

  1. Uses a standard link shortener for a redirect ( in this case)
  2. Which redirects to the phishing delivery page (a compromised page on
  3. That page however rather than hosting the HTML phishing login page directly, does this:

<script type="text/javascript">
        window.location="data:text/html;base64,... base64 encoded version of HTML phishing login page ...";

That data: URL is itself the phishing page content, which includes links to real ANZ website logos to make it look as authentic as possible, but has a form submit action to a compromised page on

This approach is interesting because it makes it impossible to report this page as a forgery using the standard Firefox "Report Web Forgery" action because Firefox thinks it’s a data: URL. Neat trick that makes it harder to remove or block in the long run.

I’ve reported this issue as a Firefox bug:

Posted in Technical. Comments Off on New phishing trick, data: URLs to avoid forgery reporting

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