Humm so back in February Microsoft did a update that left Firefox users more open to attack according to computerworld with a add-on they slipped into Mozilla "Microsoft .NET Framework Assistant"

An add-on that Microsoft silently slipped into Mozilla's Firefox last February leaves the browser open to attack, Microsoft's security engineers acknowledged earlier this week.

One of the 13 security bulletins Microsoft released Tuesday affects not only Internet Explorer (IE), but also Firefox, thanks to a Microsoft-made plug-in pushed to Firefox users eight months ago in an update delivered via Windows Update.

"While the vulnerability is in an IE component, there is an attack vector for Firefox users as well," admitted Microsoft engineers in a post to the company's Security Research & Defense blog on Tuesday. "The reason is that .NET Framework 3.5 SP1 installs a 'Windows Presentation Foundation' plug-in in Firefox."

The Microsoft engineers described the possible threat as a "browse-and-get-owned" situation that only requires attackers to lure Firefox users to a rigged Web site.

Ok so how do you tell if you have this and have exposed yourself and how do you remove it? Well you need to click on Tools up top then add-on

after that you need to look at your add-on's to see if you see it

at this point you need to either "Disable" or "Uninstall" it.

Once you do that you will need to restart Firefox