@1 Script Secure will prevent a hacker from submitting forms from outside your domain/server.

Without referrer-check protection, someone may cheat you by doing these:
Download a form from your website.
Modify the form, such as the prices, product names ....
Run the modified form and execute the existing script on your website.
You deliver your product to him although the amount of online credit card transaction is only 10 cents.

With Script Secure, the execution of your existing script will be terminated if the script does not recognize the location of the form calling it. You may specify multiple valid referrers such as:
http://www.yourdomain.com/yourform.htm
http://www.yourdomain.com/yourform2.htm
http://123.456.89.593/yourform3.shtml

Installation
Works on virtually any type of existing scripts (tested on Unix/Linux only).
Simply cut and paste the codes into the beginning part of your existing script (immediately after the line #!/usr/bin/perl or similar ...) that you want to protect.