'''This is not from Mozilla or the Firefox web browser'''. The fake firefox-patch.exe and firefox-patch.js files can install things like trojans, viruses, or unwanted software on Windows based on past reports if the user runs them. Mozilla has no need to host Firefox downloads or updates elsewhere, especially not at random weird name websites. '''The way Firefox updates are done has not changed''' over the last ten years since Firefox 1.5 as updates are done internally in Firefox (with a .mar type of file) whether on Windows, Mac OSX or Linux or by download from mozilla.org like say www.mozilla.org/firefox/all/ You could try using a adblocker extension like uBlock Origin to block theses fake ads if you keep getting them. https://addons.mozilla.org/firefox/addon/ublock-origin/ Mozilla would love to shut this down but it has not been so simple as it is more elaborate to just creating some fake sites and serving this firefox-patch.js file. Unfortunately this has gone on for over a few months now with one or two new sites reported almost everyday. https://support.mozilla.org/en-US/forums/contributors/712056/ and https://support.mozilla.org/en-US/forums/contributors/712075 https://support.mozilla.org/en-US/kb/i-found-fake-firefox-update