[support] Strange thing happened in my site - virus attack(?)

[Fahri Reza]

On Tue, 2012-06-19 at 21:43 +0000, Kim, Soonho (IFPRI) wrote:
> Dear all,
> 
> I found something strange happened in my site. As you see the attached, a user named "Anonymous" tried to update wiki pages every day. 
> The wiki page is only accessed by a certain user group (definitely not "Anonymous" user).  What "Anonymous" have done was just to un-publish page. 
> Is there anyone who is familiar with this strange case? Is there any way to delete the user and to protect this?
> 
> Thanks so much for your help in advance. 
> 
> Best Regards,
> Soonho

Also check if that Anonymous is not a cron job on your site.