Mozilla blocks Microsoft's buggy Firefox plugin

Microsoft silently installed the .Net plugin earlier this year

Mozilla developers have blocked a Firefox plugin that was quietly pushed out by Microsoft, saying that it presents a security risk.

Microsoft shipped the Firefox add-on as part of a .Net software update last February, causing outrage among some Firefox users, who complained that the software was sneaked onto their systems without their knowledge or approval and was extremely difficult to remove.

On Tuesday, Microsoft warned that Firefox users who have not applied a recent Internet Explorer patch were vulnerable to a "browse-and-get-owned attack" because of a bug in the Microsoft .Net Framework Assistant add-on.

"All that is needed is for a user to be lured to a malicious website," Microsoft said. Triggering this vulnerability involves the use of a malicious XBAP (XAML Browser Application).

The flaw is a nasty one, but users who have installed the MS09-054 IE update, released Tuesday are protected from this attack, "regardless of the attack vector," Microsoft said.

To protect users who may not have installed Microsoft's patch, Mozilla is automatically blocking two add-ons: the Microsoft .Net Framework Assistant and a related plugin called the Windows Presentation Foundation. The open-source browser started blocking the software late Friday night.

"Because of the difficulties some users have had entirely removing the add-on, and because of the severity of the risk it represents if not disabled, we contacted Microsoft today to indicate that we were looking to disable the extension and plugin for all users via our blocklisting mechanism," wrote Mozilla Vice President of Engineering Mike Shaver in a blog posting. "Microsoft agreed with the plan, and we put the blocklist entry live immediately."

Buggy plugins are a growing problem, as cyber criminals have increasingly leveraged flaws in products such as Adobe Flash Player and QuickTime to launch browser-based attacks. Earlier this week, Mozilla launched a Plugin Check site where Firefox users can see if their plugins are up-to-date.

Join the newsletter!

Or

Sign up to gain exclusive access to email subscriptions, event invitations, competitions, giveaways, and much more.

Membership is free, and your security and privacy remain protected. View our privacy policy before signing up.

Error: Please check your email address.

Tags MicrosoftFirefoxmozillaexploits and vulnerabilities

Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Robert McMillan

IDG News Service
Show Comments

Father’s Day Gift Guide

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Luke Hill

MSI GT75 TITAN

I need power and lots of it. As a Front End Web developer anything less just won’t cut it which is why the MSI GT75 is an outstanding laptop for me. It’s a sleek and futuristic looking, high quality, beast that has a touch of sci-fi flare about it.

Emily Tyson

MSI GE63 Raider

If you’re looking to invest in your next work horse laptop for work or home use, you can’t go wrong with the MSI GE63.

Laura Johnston

MSI GS65 Stealth Thin

If you can afford the price tag, it is well worth the money. It out performs any other laptop I have tried for gaming, and the transportable design and incredible display also make it ideal for work.

Andrew Teoh

Brother MFC-L9570CDW Multifunction Printer

Touch screen visibility and operation was great and easy to navigate. Each menu and sub-menu was in an understandable order and category

Louise Coady

Brother MFC-L9570CDW Multifunction Printer

The printer was convenient, produced clear and vibrant images and was very easy to use

Edwina Hargreaves

WD My Cloud Home

I would recommend this device for families and small businesses who want one safe place to store all their important digital content and a way to easily share it with friends, family, business partners, or customers.

Featured Content

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?