Yes. Anyone is allowed to contribute (contributor role) if they register first. But I don’t seem to be getting any new registrations to coincide with these spam posts. The site is brand new, so there are only 3 members. And I know all of them personally.
I installed the WordPress Zero Spam, Cookies for Comments, and Registration Honeypot plug-ins, and I’m still getting crazy Asian spam posts. It’s not in the comments section. They’re actual blog posts.