I knew I had a virus on my Mac and I couldn't immediately find the offending files. So I found a few reviews for FreshMac and purchased it, using the logic that hey, those free virus scanners I've used in the past were only ok, maybe this one will be GREAT because it's not free.
Freshmac DOES NOT WORK to remove the Bing redirect virus that I had on my computer.
What DID work for me was to open the command line terminal and show the applications on my Mac; two folders showed up there that were not visible in my Finder window. They were both variants on the name Advanced Mac Cleaner. This is a virus that I accidentally downloaded months ago and thought I had gotten rid of. Once I removed those folders using the terminal, I then used Finder to search for and remove 4-5 more files that contained those search terms (Advanced Mac Cleaner).
I reinstalled Firefox and the problem is solved, no redirects. I wish I had done that before purchasing that worthless program, FreshMac.