These are the malware detection and security Apps I use and recommend.
KnockKnock - This checks for anything that persistently launches across reboots, something that plenty of legit software does, but certainly is also a hallmark of malware…
Malwarebytes - Speaking of malware, this is still the best anti malware app for Mac in my opinion… They’ve slowly ratcheted up the annoyance factor over the years in terms of bugging the user to “go premium” unfortunately. On the Mac, I still don’t see the value in paying for constant scanning though, assuming you’re running one of the last two or three versions of macOS, and also don’t have a habit of installing random dodgy software from goodness-knows-where!
Little Snitch - This App is an outgoing firewall, which is to say it monitors outgoing network connections from all Apps and lets you allow or deny them, based on a set of configurable rules. I have run it on and off since 2006.
Currently listening: Dee Camù - “Liquid Drum & Bass Mix - Home Session After The Gym”