Neil Turner's Blog

Blogging about technology and randomness since 2002

Fixing Windows Genuine Advantage on Firefox

Recently Microsoft launched Windows Genuine Advantage, a tool that prevented the installation of various Windows add-ons on non-genuine (i.e. pirated) copies of Windows. Originally this was an ActiveX control that only worked in Internet Explorer but since then a plugin for Firefox has been released which will allow Firefox users to validate their copies of Windows in the same way that Internet Explorer users can at present.

The plugin is simple to install – you’ll probably need to be an administrator to do it, unless you run Firefox from a local profile or something. The bad news is that it doesn’t always work.

Thankfully there’s a workaround. The package you download is actually a glorified .zip file, so all you need to do is open it in a program like WinRAR or WinZip and extract the contents somewhere. You’ll then have 3 files: npLegitCheckPlugin.dll, nsILegitCheckPlugin.xpt and PluginInstaller.exe. PluginInstaller.exe is no use to us, so you can discard it.

Close Firefox, then copy npLegitCheckPlugin.dll to your Firefox plugins folder, which will probably by C:\Program Files\Mozilla Firefox\plugins.

Then copy nsILegitCheckPlugin.xpt to your Firefox components folder, which is usually C:\Program Files\Mozilla Firefox\components. Now, relaunch Firefox and you should be ready to go.

What’s more, you can use this method for other browsers like Netscape and Mozilla, and probably even Opera, though I haven’t tried them yet. If you do, you may have to change the user agent of the browser to Firefox – in Mozilla and Netscape, type about:config in the address bar, then right click somewhere and select ‘New’ followed by ‘String’. Call the value ‘general.useragent.override‘, click OK, and then type ‘Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv: Gecko/20060111 Firefox/‘ to give it the Firefox for Windows XP user agent.

The details for this came from the PluginDoc web site, which has links to almost all browser plugins available for Firefox. There’s a lot out there.


  1. Now you’ve got me wondering if I’m missing summat – why would you need to validate Windows XP (in Firefox or anywhere else)?

  2. Essentially it’s because Microsoft won’t let you download certain Windows add-ons without it. They include the newly-released Windows Defender. Microsoft are trying to crack down on pirated copies of Windows by offering an incentive to use a legitimate copy. That said, if you bought your computer and it came with pirated Windows, Microsoft will give you a free legitimate copy in return for information about the seller.

  3. Hey could you post up a collection of your favourite / reqularly visited technology news and interest websites…
    e.g. downloadsquad etc.

  4. Alternatively, you could save yourself the trouble, and use IE !!

  5. Above:
    That must be the most stupid comment of the year.

  6. Why is suggesting to use IE stupid? It does the job. Sure, you shouldn’t have to use it but it works and doesn’t require workarounds like this.

  7. Yes indeed. why go all the way to install a plugin for firefox rather than quickly finish off using IE. unless you accidentally set IE as ur default browser you would be well off using firefox for ur surfing activities.

  8. i need help i found out that my windows is a real copy is there anyway i can get round this

  9. Sorry but i think that tops off as the most stupid comment on here

  10. I understand the impetus behind WGA in that it’s designed to thwart piracy. BUT, once it is determined by WGA that the operating system is perfectly legitimate, why isn’t that enough for Microsoft?
    Tell me why that bloated software (WGA) has to connect to the Microsoft servers on every start-up in order to constantly validate the operating system, especially after it has already been validated/passed inspection?
    This slows my system down to a crawl as well…making me one very unhappy customer. Grr.