Cryptocurrency miners hacked my blog

You can never be sure you've found all the backdoors.

Make sure you have backups stored somewhere that your web host/server cannot alter. Make sure you have a plan on how to reinstall whatever OS and blogging software you need from the ground up.

Do not trust p0wnd boxes ever again.

The first thing I would recommend in this case would be "use a static site generator for your blog". I don't think it makes much sense to have a dynamic blog, usually, and you are immune to these problems.

"Both are hosted and built on WordPress." As I expected when reading the headline.

Oh yeah, I got the pleasure of cleaning 10+ boxes with WP a few months ago. Nasty stuff.

Nitpick @title: miners aren't hacking your boxes, hackers are mining on your hacked boxes.

Don't use wordpress...