Hi &nbsp; ! Good for you to be on the alert, for mc.yandex.ru is malware, that you of course need to get rid of. Go to the 3-bar menu => Addons => Extensions and look for any unfamiliar or suspicious looking extensions, like e.g.: When you find any : &nbsp; remove them. Also look in : 3-bar menu (or 'Tools') => Options => Advanced => Network tab => Under : 'Offline Web Content and User Data' However : &nbsp; most malware will be 'hiding' somewhere , so let's run malware scans : Further information can be found in this article : <BR> https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware?cache=no <BR> '''Run most or all of the listed malware scanners.''' <BR> They all work differently &nbsp; - &nbsp; what one program doesn't pick up, the other might. Also see : https://malwaretips.com/blogs/remove-yandex-ru-search/