I can well imagine that you cannot imagine what that all has to do with your site. It is with your hoster, where they did sloppy IT managment.
That server has serious security issues to be abused by attackers. You have to take this issue up with them.
By the way burleigh dot ohbees dot com dot au is also being blocked by avast webshield as URL:Mal…web shell vulnability…>
http://www.w3bsecurity.com/warning-wordpress-plugins-vulnerability-list-from-2004-to-2013/

polonus