I'm not sure but suddenly it appears message like my image.

How is this possible as PC did not report any malicious code.

about:newaddon?id=bingsearch.full@microsoft.com

There are reports that this is connected to Windows10 but I do not know. Example: http://www.computerworld.com/article/2979791/web-browsers/microsoft-pitches-edge-on-bing-to-deflect-deserters.html Need help

Looks like Microsoft is "pushing" Bing on their users, and they're trying to install a Firefox add-on, Strange ... because at least in the USA, a Bing search plugin has come standard with Firefox for quite awhile now.

I do have a concern that "it" may be more than just a "simple" search plugin; the installation of that add-on might "lock-in" Bing as the "default" search engine and make it hard for you to change your "default".

Overall, Microsoft can do as they please as far as installing any software on your PC as they see fit, as long as "Windows updates" are enabled. And that is the "default" with the Windows Operating Systems; although the user can disable "automatic updates", at least with versions before Windows 10.

Allow it or not, that choice should be yours - but the add-on installation may not go thru, if that add-on wasn't signed by Mozilla. And if you do allow it t proceed, please let us know if Firefox blocks it due to "not verified" or mention of not being "signed". And also if you encounter any issue with Bing making itself the "default" search engine or resetting the "default" back to Bing. This might turn out to be a situation that Mozilla needs to be informed of.

Due to security I will not click any links if I do not accept and per Mozilla instructions. I'm not sure but yesterday it was installed new version of Skype. Maybe this is the reason. I have to see if there is malicious code.

I have checked again. There was installed Bing Add-on. I'm not sure but I have removed this Add-on.

Yes, that Skype update or installation might have been the entry point. I forgot to mention that the installation of other Microsoft applications could possibly include an add-on for Firefox; I was 'stuck' in a Windows Update mindset as being the probable source..

The Remove button should remove that Bing Search add-on, but as long as it doesn't cause any problems I wouldn't worry about just being there and (disabled). Getting rid of it might just bring about another installation at a later date. I would expect MS to pull something like that....