Fast forward to last night. I click on a bookmark for Craigslist, and up pops a new tab displaying a page from the Flash and Video Download addon (http://fnvfox.appspot.com/thankyou.html). I quickly closed it. I go back to browse and I notice new icons on the Firefox toolbar. Then I notice they're not really new: they are icons for the addons that I had prior to refreshing Firefox a couple of months ago. I open up Addons Manager, and they're all back--one of them being the Flash and Video downloader (which shows its last update as October 30, 2015, the night this occurred). Then I clicked on a link to a website, and Firefox kept popping up prompts asking me if I wanted to accept cookies for the site--which was what I had configured Firefox to do before I refreshed it, but not after. I went to look at my profile. I had a shortcut to the new profile created when I refreshed; the shortcut's target was gone. The profile no longer exists.
I've searched the web, but can find no similar reports, although I have seen reports of Flash and Video Downloader opening a new Firefox tab on its own, without being asked. I ran Malwarebytes and a full system virus scan with Avast, and they found nothing unusual. There is obviously some connection to fnvfox.appspot.com, but what? How could this change have been effected? Has anyone heard of anything like this?
Edited by Queen-Evie, 01 November 2015 - 07:28 PM.
moved from Web Browsing/Email and Other Internet Applications to Am I Infected for a malware check