Actually a tool by the author of the book:

https://objective-see.org/products/knockknock.html

Recommend all of the tools that Patrick has created:

https://objective-see.org/tools.html

I will second both recommendations made here. Wardle's tools comprise a majority of my suggested macOS security stack on machines at work now.

Nice thanks for sharing

I completely agree with you. This article is nothing but pandering for notability by publishing something that attempts to scare the reader.

I'm all for pushing O.S and Browser vendors to remove many of the trusted certs in the root store...but this is just silly and frustrating.

Articles like this make the security industry lose credibility.