If you thought backdoors
were only on houses this MalwareBytes article
has details on how one might be installed on your Mac without your knowledge and is complete with less technical written descriptions as well as code samples of Mac specific
exploits. Their entire Cybersecurity Basics
is informative reading for anyone wanting to learn more about online security. DISCLAIMER:
I have no relationship, pecuniary or otherwise, with MalwareBytes other than being a customer.