Are you asking if this is legit? '''This is not from Mozilla or the Firefox 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 random name of the websites alone should raise a flag that it was not legit. It is coming from some malicious Ads on some websites. They are trying to trick less experience Windows and or Firefox users (on Windows) to run this fake firefox-patch.js file. Even if you were to download this firefox-patch.js file it is not a risk unless you were to try and run it. The Firefox updates have not really changed as they are done internally in Firefox (with a .mar type of file) whether on Windows, Mac OSX or Linux (since Firefox 1.5 about eleven years ago) 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 a while now with one or two new sites still reported every so often though not as much in last couple months. https://support.mozilla.org/en-US/forums/contributors/712056/ https://support.mozilla.org/en-US/kb/i-found-fake-firefox-update