https://www.vice.com/en_us/article/wx5855/massive-mac-apple-security-bug-malware-hack

Hackers have been exploiting a previously unknown bug to hack into an unidentified number of Mac computers, according to security researchers who found the flaw and analyzed it.

The bug allowed hackers to create malware that could take control of a victim's computer, bypassing Apple's security protections on MacOS, such as Gatekeeper, File Quarantine, and app notarization requirements. These mechanisms in theory block files downloaded from the internet from accessing user files unless they are signed by known developers and have been checked by Apple for malicious software, as the company explains in official documentation.