includes/functions_referrers.php
FIND
$ref_black_list = array(
'.wst.st',
'.neyon.com',
'.byethost',
'cialis.w48.54.ru',
'.volja.net',
'.siol.net',
'.alice.it',
'xoomer.alice.it',
'.skynet.be',
'users.skynet.be',
);
'.wst.st',
'.neyon.com',
'.byethost',
'cialis.w48.54.ru',
'.volja.net',
'.siol.net',
'.alice.it',
'xoomer.alice.it',
'.skynet.be',
'users.skynet.be',
);
Add the domain you wish to block... and check if it works.
ex:
P.S.: another suggestion is to set Referrers Permissions to REGISTERED users or above in ACP => Configuration => Page Permissions.