Starting with Firefox 8, Mozilla will automatically block browser add-ons installed by other software until users approve them, a company product manager announced yesterday.

Software-bundled add-ons have been a problem for Firefox users, who have sometimes been surprised to find browser extensions show up on their machines without their consent.

An add-on included with Skype, for example, caused such a high number of browser crashes that Mozilla added it to a list of banned extensions last January. And in 2009, an add-on that Microsoft silently slipped into Firefox left browser users open to attack, a fact that Microsoft itself admitted.

"While some of these applications seek the user's permission beforehand, others install add-ons into Firefox without checking to make sure the user actually wants them," said Justin Scott, product manager for add-ons, on a Mozilla company blog .

More: http://www.pcworld.com/article/237967/