
140 Chapter 4 • Vulnerable CGI Scripts
common mistakes and following good practices when creating CGI
scripts, you can write tighter code that prevents your system from being
attacked. Some of the problems we’ll discuss here regard controlling per-
missions, user input, and using error-handling code.
In creating CGI scripts, you will probably create an interface that
will access your CGI program. In most cases, this will be a form that
allows users to enter data on a Web page. Upon clicking Submit, data is
then passed to the CGI program to be processed. However, while this is
the common method used to access CGI programs, it is important to
realize that ...