how can one be rid of this exploitation or secure up the script?

It's almost certainly an automated process, so have you considered using a CAPTCHA?

TJ

Please bear with me - I'm no fundi with these things and the CGI script exploitation on the server. Please give me more info or let me have a procedure to follow.

Is there software to monitor or "catch" this auto-bots?

Thanks for any help.

There is some discussion of this here:
How to block a spam bot with changing IP address [webmasterworld.com]

A captcha is an image that you display to the user so the user has to read and enter what's in the image... this in general makes it hard for 'spam bots' to submit your form.

Some of the other suggestions in that thread, such as checking HTTP_REFERER are pretty good also. None of these ideas are foolproof but they might help.

You might also consider 'locking down' (not accepting new posts) on your current guest book program, link to it as the guest book archive, and start using a newer program that implements some sort of spam prevention ... this way you don't have to do any coding and the spam will stop or slow down. Or there might even be an upgrade for your current guest book script that includes some spam-blocking features.