Question. Spam accounts in your wordpress blog

I have a WP blog, and I notice that almost everyday is someone new registered in it. That would be nice if they were real users, but they are not. It looks quite like automatic or random names (xuxyrahe, wwcozz ... etc.).

My question is: What is the purpose of doing something like that? What is the winning of registering "fake accounts" in other's wordpress blogs?

Please feel free to share your opinions about this. Thanks a lot for your time reading.

They're hoping to find poorly secured websites. I'm sure there are WP blogs out there with the default role for new users set to author or above. In that case they could post tons of spam directly as blog posts.

The easy way is to disable the new user register.

It may get impression of using fake accounts

It's part of a 2 step process, 1st the account is registered then on the second pass a post will be attempted.
My last auto-blog was bringing in 500+ accounts a day until I put in protection.

recaptcha will not stop most but there are loads of ways of stopping this.