Hi, have you launched a scan with your antivirus?

Hi ! Firefox will always update from within the browser and not from a random webpage. Scammers have been using this tactic, trying to get users to download and infect their computer. Hard to get rid off, as they will change their URL on a daily basis. You could consider an ad-blocking add-on like : https://addons.mozilla.org/en-US/firefox/addon/ublock-origin/?src=ss Also see : https://support.mozilla.org/en-US/kb/i-found-fake-firefox-update As you seem to have opened it, it's best to do as suggested by 'smorele': Troubleshoot Firefox issues caused by malware : https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware