For cPanel servers, log in as root and run the following:
chmod 0000 /usr/local/cpanel/base/cgi-sys/mchat.cgi
chmod 0000 /usr/local/cpanel/base/cgi-sys/cgiecho
chmod 0000 /usr/local/cpanel/base/cgi-sys/cgiemail
chmod 0000 /usr/local/cpanel/base/cgi-sys/guestbook.cgi
chmod 0000 /usr/local/cpanel/base/cgi-sys/Count.cgi
chmod 0000 /usr/local/cpanel/base/cgi-sys/countedit.cgi
chmod 0000 /usr/local/cpanel/base/cgi-sys/formmail.cgi
chmod 0000 /usr/local/cpanel/base/cgi-sys/FormMail.cgi
chmod 0000 /usr/local/cpanel/base/cgi-sys/FormMail-clone.cgi
chmod 0000 /usr/local/cpanel/base/cgi-sys/formmail.pl
chmod 0000 /usr/local/cpanel/base/cgi-sys/FormMail.pl
It will disable FormMail and other very exploitable scripts.
