It's fine now, i've found 2 injectors files in "Wordpress and vBulletin", it was a malware program entered via Wordpress "Uploads" folder named : wp-pass.php and tooper.php.
These 2 files contains some PHP codes for redirectionning people to malware links, to steal crecedential informations etc, then they go to vBulletin files. So the problem was found from "Wordpress bug security v2.2"
Regards.