April 12, 2008 4:05 PM PDT

Tracking down Firefox plug-ins

Posted by Michael Horowitz

My last posting was about upgrading the Adobe Flash Player, a Web browser plug-in. Adobe Systems just released a new version that fixes critical bugs in older versions, so everyone should update to the latest version.

Adobe's Flash tester page displays the version of the Flash Player being used by your Web browser. Sometimes though, the Firefox results may not be what you think they should be. I've run across a couple instances in which Firefox was not using a newly installed version of the Flash Player.

The rules for where or how Firefox loads plug-ins have changed over time, and all software vendors may not have a perfect understanding of them. Then too, many uninstallers leave files behind; it's almost the rule rather than the exception. If your copy of Firefox isn't doing what it's supposed to do, there are two ways to find out from where it picked up a particular plug-in.

Start Firefox, and in the address bar, enter "about:config" without the quotes (see above). In the filter bar, enter "plugin", again without the quotes. Double-click on "plugin.expose_full_path." This should change the value from "false" to "true" and the status from "default" to "user set."

Go back to the address bar, and enter "about:plugins" (no quotes). As shown below, the file name in the Shockwave Flash section has the name and the full path of the file Firefox is using for the Flash Player.

If there is no Shockwave Flash section, try visiting a Web site that uses Flash. Adobe's Flash tester page is a good choice.

You can also use the excellent Process Explorer program from Microsoft to see which DLL Firefox is using for the Flash Player. In Process Explorer, click on the running instance of Firefox, click the button to show the lower pane, then use the button next to it to ensure that you are viewing DLLs rather than Handles.

Sort the list of DLLs by company name so that Adobe files appear near the top. The current flash DLL is NPSWF32.dll. To see where it came from in the local file system, either hover the mouse over the name of the DLL or double-click on it to open a properties window that shows the file location.

This detective work is especially important when dealing with portable versions of Firefox. More on that soon.

See a summary of all my Defensive Computing postings.

Originally posted at Defensive Computing

Michael Horowitz is an independent computer consultant and the author of several classes on Defensive Computing. He is a member of the CNET Blog Network, and is not an employee of CNET. Disclosure.