It sounds like you are getting a random named website claiming to have a urgent update. '''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, unwanted software or to download additional stuff onto Windows based on past reports if the user runs them. The 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/ Unfortunately this has gone on for several weeks 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