No it is not legit. The scammers are hoping to trick inexperienced Windows and or Firefox users into downloading and running this fake .exe without scanning first. The fake firefox-patch/firefox-update .exe can install things like trojans, viruses or unwanted software based on past reports. The desktop Firefox is not just for Windows as it is for Mac OSX and Linux also so .exe would '''not''' be an effective way to send out Firefox updates. The updates are done internally in Firefox (with a .mar type of file) or by download from mozilla.org like say www.mozilla.org/firefox/all/ Even if Mozilla were to use .exe for Firefox updates on Windows, they would be serving them from a *.mozilla.org url and not from random websites with weird names. Report fake Firefox updates sites like this as "distributing modified Firefox/malware" at https://www.mozilla.org/legal/fraud-report/ (url is at bottom of many mozilla.org sites) and Google may block if reported enough at https://www.google.com/safebrowsing/report_phish/ which can be accessed by Help > Report Web Forgery in Firefox. Also could be reported as spam abuse at say http://publicdomainregistry.com/report-abuse-2/ since they have been the Registrar of these fake Firefox updates scam sites. I have a thread about these sites serving a fake firefox-update/firefox-patch .exe at https://support.mozilla.org/en-US/forums/contributors/712056