Can’t access WordPress Dashboard – botnet attack?

Hello,
I’m currently unable to access my websites’ wordpress dashboard – when I attempt to do so (or visit the site at all, actually) I am presented with the following:

“Due to botnet brute force login attack, use the following credentials to access wordpress, Username: wordpress, Password: wordpress.
Press reload in your browser to try again.”

So far I have declined to use this login data because it strikes me a fishy – any ideas on what’s happened here?

Thanks in advance.