Follow the steps described below to reproduce the security vulnerability:

1. Go to http://www.gemsbarbados.com/guestbook.asp?sign
2. Enter the script written below in the Name text field:
script>alert('This Site is vulnerable to XSS');
3. Enter the script written below in the message area:
XSS ATTACK by AMIT
4. Submit the form by clicking Sign guestbook button.

It will show the javascript alert and will also execute the blink command. So the site has security bleach.