Hi ! Good for you be on the alert ! This is a fake ! 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 I don't think you did, but just in case you opened it : https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware