Site Attacked

[cammot]

I need some urgent help. It seems that my vB4 suite site has been attacked by a hacker. What has happened is that a new section has been added to the list of sections on my home page. The new section is an advertisement with some profanity on it. Clearly, who ever did this may have had access to my CP, and add the new sections.

Aside from trying to determine how this might have happened, I am unable to delete the section becasue there is no 'delete icon' next to it. I am however, able to block the viewing on the front end of this specific section, by removing all the permissions except to the administrator.

I recently updated the latest patch 4.0.2 so not sure how this has occured, and how to prevent it from continuing - and also removing the section.

Any help would be greatly appreciated.

cammot