Detecting Firefox Extensions

I got this idea from J. grossman. I extended it to list over 50 Firefox extensions. If a visitor has installed those extensions, this page can detect them.

You might be advertising the fact that you have installed hacking tools, that you have a facebook membership, that you surf using TOR to hide your identity, or even that you have installed an extension with security flaws. If you are using a public computer and wish to see which extensions are running behind the scenes, this is one way to do it.

The detection relies on javascript. There is a long discussion here on the Firefox bug list about whether to fix it. Apparently, they decided not to.

The script tries to load images associated with the extension from a chrome://… type resource. Most of the extensions I’ve tried are detectable. Some use no images at all and so this method won’t work.

There is a certain amount of path guessing involved, but most of them can be found at chrome://[extensionName]/skin/logo.png or chrome://[extensionName/skin/[extensionName].png

There are certain cases, like with greasemonkey on Mac, in which I can’t detect the extension. I suspect it is just me who can’t find it rather than any prevention in place. Also, different versions of the same extension keep their images in different places, so your version may not trigger a hit on my list.

Let me know if there are any false results.

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About Tim

Minneapolis Blogger
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4 Responses to Detecting Firefox Extensions

  1. MattM says:

    I have no extensions!

  2. Tim says:

    better get you some. I had about 8 before I compiled this list. Now I have over 60

  3. Alcides says:

    Can you guess the name to Seatbelt?

    (if you don’t know, seatbelt is a OpenID integrations with Firefox).

    I am detecting it for it’s effects, but I wanted to know if it was installed.

    Thank you

  4. Tim says:

    here ya go: