Had never heard of it - so, I did a search and came up with this:
Firefox Spyware infects IE?
What if there was an infection out there that could bypass Firefox and still get its grubby little paws on IE, and from there, the heart of your OS? What if that same infection could get past not only FF, but a whole raft of other (supposedly more secure) browsers too?
In http://reviews.cnet.com/5208-6620-0.html?forumID=14&threadID=181250&messageID=1982299 a member notes:
"Just installed a new Internet Security Suite, and guess what? On a Spyware check, it informed me that the Firefox Browser was recording my mouse clicks and keystrokes and was sending them back to a server!
I always thought the Firefox was the most secure Browser -- acording to the New York Times -- I guess they got it wrong this time like most other times!"