Antivirus One is an app in the Mac App Store and it is free to download and install. That app has been replaced by an even better app called Antivirus One - Virus Cleaner. However, it was improved and the resulting app was much better. When I first looked at this security app from Trend Micro, it was called Dr Safety had some irritations and was disappointing. More security: Protect your Mac when using the internet with a VPN It is not impossible though and you must be wary. Email is a potential source of malware, although it is mostly aimed at Windows users, so as a Mac user you are less likely to be affected by bad attachments. If you see links or ads for free commercial apps for the Mac, just don't go there because that is how you get malware. The Mac users most likely to get malware are those that install apps from bad websites, torrent sites, and similar places where cracked apps can be found. You sometimes see these people complaining in Facebook groups and other places and asking how to remove it. Not everyone needs extra security on their Apple Mac, but some people clearly do as malware, mostly adware, but occasionally more serious threats infect their computers. You need protection or at least detection. There has been an increasing number of reports of malware on the Apple Mac recently and it is no time to be complacent.