Is macOS’s new XProtect behavioural security preparing to golive?

A third XProtect was discovered in Ventura, this time observing potentially malicious behaviour such as attempts to access private data for browsers and messaging apps. This XProtect Behaviour Service (XBS) has used a set of Bastion rules embedded in the strings in syspolicyd to record behaviours in a new database, but so far has been an observer and hasn't blocked such behaviours. Security researchers have already been able to discover its records of novel malicious code, and Chris Long has documented how to access its database, but so far syspolicyd has only watched and recorded.

Recent descriptions of Bastion rules have identified four, last updated in syspolicyd in macOS 13.5 on 24 July 2023. Those changed on 8 August, when Apple released its first update to the Bastion rules, and again a month later on 1 September, when they changed again. There's now a fifth Bastion rule, and XBS appears to be getting ready to fly for the first time.

If you had told me in 2005 or so, when I was a fervent Mac user, that one day, macOS would come with an extensive set of antivirus and antimalware tools that ran silently in the background, checking everything you do on your computer - I'd have thought you were crazy.

But here we are.