How are Common Gateway Interface (CGI) script intrusions implemented and prevented?

What will be an ideal response?

If the Web server isn't configured correctly, a remote user can run CGI scripts as a root user. The file system is a major vulnerability, so a remote user might be able to install and run a CGI script from a poorly secured /tmp directory and gain unauthorized access to the server. Configuring the Web server to run CGI scripts only from specified locations prevents CGI script intrusions.