So you are getting a random name website page claiming to have a so called urgent update for Firefox and a prompt to download a fake '''firefox-patch.js''' file. The random name of the website alone should raise a flag that it was '''not''' legit. '''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 Firefox 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/ Firefox 48.0 has been the current Release since Aug 2nd. https://www.mozilla.org/firefox/48.0/releasenotes/ 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