Okay, you're writing a CGI script in perl and you want security.
Have perl check for tainted data. (the -T command line option).
Some advice that's not security related but good anyway, tell perl to show you warnings ( -w ) and errors (use strict).
Something like:

#!/usr/bin/perl -T
use strict;
use warnings;
[download]

or:

#!/usr/bin/perl -wT
use strict;
[download]

Update:Reworded the part about warnings and strict

---

Who says that programmers can't work in the Marketing Department?
Or is that who says that Marketing people can't program?