my site got attacked ,please help.
 

everything looks fine but .../furums/index.php
they added script after the body tag
Code:
// ### ALL DONE! SPIT OUT THE HTML AND LET'S GET OUTTA HERE... ###


/*================================================= =====================*\
|| ################################################## ##################
|| # Downloaded: 11:41, Tue Mar 31st 2009
|| # CVS: $RCSfile$ - $Revision: 28997 $
|| ################################################## ##################
\*================================================ ======================*/
?>




I have renamed index.php and uploaded the original index.php
my site get back but I want to know how to protect my site from this spam/script.

Thanks for your help.

Regards,
Panus

ps. I have been updated to 3.8.2
http://www.thai3dviz.co.th