octagon-com.apple.security.keychain - 'unknown'

Malwarebytes is one of the few and programs that the experts in these Discussions actually recommend for removing malware.

Many of us go along for decades with no malware issues. I have never had such a problem. I think the key is to never click links in emails, and be very careful about visiting questionable sites. Also, download software only from reputable sites and providers. Never enter your password unless you initiated the activity yourself.

In your instance, I think the complete erase/reformat/wipe of the physical drive will restart you in a fresh uninfected state. And change all your passwords before putting anything on your "new" Mac.

Try downloading Malwarebytes (free version) to scan your Mac computer for malware and to remove it. If this does not work completely for you, then do the following:

Use Finder copy to make a copy of files you want to keep, copy them to an external drive. Copy the files you want from your Documents folder, Desktop folder, Pictures folder, etc.

After you have at least one copy of everything that matters to you, boot the Mac into Recovery COMMAND-R and use Disk Utility to erase/format your drive and install a new operating system. You can follow these instructions, they will allow you to wipe the computer clean, as if you were about to sell it or give it away. Of course you plan to still use it, but these are the instructions to follow.

https://support.apple.com/en-us/HT201065

You must have copies of the files that matter to you before doing this as it completely wipes your drive clean.

After doing this, you can boot up and create your user account from scratch (not from a backup). Then copy those files you saved form the external drive. This will bring over none of the malware, just individual files.

Just to be sure, you can download Malwarebytes (free version) and run it to verify that there is no malware on this "new" Mac.

After that, you can continue to use Malwarebytes (the purchased version has more options) and be extra careful about sites you visit, what you click on, and what you install.