It is a false positive. If it was truly infected with something it would not have only one result but multiples. Cylance, Antiy-AVL, Clam and Norton has been among a short list that has given plenty of false positives at Virustotal and in AV client over the years with Firefox setups and especially the small stubs for windows. I checked en-CA 78.0.2 win64 firefox .exe and MaxSecure was green though it was the only one red for en-US locale. Other locales do not get this single false positive while the en-US may with MaxSecure on Virusetotal based on some research. It looks like it is having the usual issues with 7zS.sfx if you look on details page. Firefox setups for Windows have been self-extracting 7z since Firefox 0.8 (Feb 2004). 7zS.sfx is the 7-ZIP self extractor stub from 7-ZIP that is used by Mozilla to pack the actual Firefox program with the 7-ZIP archive utility. ex: https://www.reddit.com/r/privacytoolsIO/comments/gptqzf/windows10_firefox_malware_check/ https://www.reddit.com/r/firefox/comments/hni6cr/is_the_official_firefox_installer_infected_by/ ex: [https://bugzilla.mozilla.org/show_bug.cgi?id=1468067 Bug#1468067] - Firefox installer doesn't pass VirusTotal test