Mozilla plans to automatically block nearly all Firefox plug-ins

Mozilla announced Tuesday that it would automatically disable all plug-ins in Firefox except the latest version of Adobe's Flash Player, citing security and stability reasons for the move.

The feature, called "click-to-play," has been part of Firefox since version 17, which launched last November, but Mozilla will restrict plug-ins even further going forward.

By default, click-to-play bars plug-in play, but users can override the block by clicking any grayed-out content area on a Web page. The technique has become popular as browser makers try to keep users safe from a rising tide of exploits that leverage bugs in plug-ins, particularly the Java browser plug-in.

Previously, Firefox's click-to-play only kicked in for those plug-ins that Mozilla determined were unsafe or seriously out of date. (The company posts a list of those plug-ins here.)

As of Tuesday, Firefox also blocked versions 10.2.x and older of Flash Player, the first step toward the goal of barring virtually all plug-ins.

The current version of Flash Player is 11.5.x on OS X Snow Leopard, Lion and Mountain Lion, and on all editions of Windows with the exception of Windows 8, where the most up-to-date is 11.3.x. OS X Tiger and Leopard's current Flash is version 10.3.x.

Although Mozilla did not define a timeline, it will soon block all plug-ins other than the latest version of Flash. The block will include up-to-date versions of popular plug-ins such as Adobe's Acrobat Reader, Microsoft's Silverlight and Oracle's Java.

Java has been especially iffy of late. Earlier this month, exploits of a critical vulnerability in the Java plug-in were found packaged in several crimeware toolkits, and while Oracle quickly patched the bug, researchers first warned that the fix was itself flawed, then claimed an important Java anti-exploit defense could be circumvented. The U.S. Computer Emergency Readiness Team (US-CERT) has recommended that browser users disable the Java plug-in until further notice.

Mozilla said the drastic step was needed to safeguard users from "drive-by" attacks, which trigger exploits as soon as a victim visits a malicious or compromised website.

The open-source developer also cited stability reasons for the move. "By only activating plug-ins that the user desires to load, we're helping eliminate pauses, crashes and other consequences of unwanted plug-ins," said Michael Coates, Mozilla's director of security assurance, in a Jan. 29 blog post.

Mozilla will be the first browser maker to disable the bulk of plug-ins by default. Chrome and Opera Software's Opera also include click-to-play, but both leave it turned off until the user enables the feature.

Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, or subscribe to Gregg's RSS feed . His e-mail address is gkeizer@ix.netcom.com.

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