Cannot install plugins for Firefox when using data control rule to block image and archive transfers in Firefox

Issue
You have configured a data control rule to block images and archive transfers if the destination is Firefox. Now you are trying to install Firefox plugins, but it isn't working.

Known to apply to the following products and versions
Enterprise Console 4
Endpoint Security and Control 9

What to do

You can temporarily allow image and archive transfers in Firefox before installing plugins. When you've installed the plug-in, switch the protection back on.

Technical information
Firefox plugins are stored in .xpi fprmat, which is a type of archive file, so the data control scanner correctly blocks their transfer.