. https://blog.malwarebytes.com/101/2019/02/macos-protect-malware/
blog article
Mac users often are told that “Macs don’t get viruses.” This is not really true, of course. Macs can and do get infected. However, it is true that macOS provides some basic protection against malware. This protection can be quite effective in some ways, but, unfortunately, quite ineffective in others. Let’s take a look at how macOS features protect you from malware, and how malware can get past these features. Quarantine. macOS has a feature that is called Quarantine. Any time a file is downloaded from the Internet, it gets marked with a Quarantine “flag.” When you try to open a downloaded app with this flag set, macOS will kick off a whole bunch of checks. If all of those checks are successful, macOS will display a message alerting you that you’re opening an application downloaded from the Internet, which you’ll have to allow if you want to use the file. (macOS flashes this message to users to display the true nature of the file, in case it was disguised as another type, for example, an app disguised as a document.). READ MORE