No, it does not - you might be infected though. You can try these free programs to scan for malware, which work with your existing antivirus software: * [https://www.microsoft.com/en-us/wdsi/products/scanner Microsoft Safety Scanner] * [http://www.malwarebytes.org/products/malwarebytes_free/ MalwareBytes' Anti-Malware] * [http://support.kaspersky.com/viruses/disinfection/5350 Anti-Rootkit Utility - TDSSKiller] (for more info, see this [https://www.bleepingcomputer.com/download/tdsskiller/ alternate TDSSKiller download page]) * [https://www.malwarebytes.com/adwcleaner/ AdwCleaner] (for more info, see this [http://www.bleepingcomputer.com/download/adwcleaner/ alternate AdwCleaner download page]) * [http://www.surfright.nl/en/hitmanpro/ Hitman Pro] * [http://www.eset.com/us/online-scanner/ ESET Online Scanner] [https://support.microsoft.com/help/14210/security-essentials-download Microsoft Security Essentials] is a good permanent antivirus for Windows 7/Vista if you don't already have one. Windows 8/10 have antivirus protection [https://www.microsoft.com/windows/windows-defender built-in]. Further information can be found in the [[Troubleshoot Firefox issues caused by malware]] article. Did this fix your problems? Please report back to us!

''Ray.H [[#question-1209576|said]]'' <blockquote> See "The state of Mac malware - Malwarebytes Labs | Malwarebytes Labs 16/03/2018, 10*56 (page 3 of 8)". </blockquote> No version of Firefox for Windows, Linux, or Mac from mozilla.org or www.mozilla.org/firefox/all/ has ever had a miner built in. It would be a very hot topic if it was true. The issue you missed was the MacUpdate website was hacked and if downloaded Firefox 58.0.2 from there instead of from Mozilla.org then you may have a modified version with a miner tool.

Mkll, the OP is on Mac OSX and not Windows as the majority of your post is for. Also this was more of a question vs being possibly infected.