I have been reading up on web security and I am getting paranoid. I operate under taint mode - although I must confess to being a little in the dark as to what that means. I am using the following code in order to filter input from a form.

$TEST =~ s/[^a-zA-Z0-9@\/.,: ]//g;
[download]

It works as expected but I am trying to make it as secure as possible and found that if a user enters '<SCRIPT>' into a form field it treats it as a Java Code and it is not filtered. I assume that I could follow this with some other code and do some harm. I need to avoid this security hole and obviously I could check for the word '<SCRIPT>' in STDIN. Is there a better way of doing this and what other holes should I be aware of?

2006-03-27 Retitled by planetscape, as per Monastery guidelines
Original title: 'audio program'

2006-10-07 Unapproved by planetscape once evidence of habitual plagiarism uncovered.