source: https://www.securityfocus.com/bid/2106/info A vulnerabiliy exists in Leif M. Wright's simplestguest.cgi, a script designed to coordinate guestbook submissions from website visitors. An insecure call to the open() function leads to a failure to properly filter shell metacharacters from user supplied input. As a result, it is possible for an attacker to cause this script to execute arbitrary shell commands with the privileges of the webserver. Make a html form similar to: Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â