Sosci Survey 2.x Bypass / XSS / Command Execution

`SEC Consult Vulnerability Lab Security Advisory < 20130417-0 >  
=======================================================================  
title: Multiple vulnerabilities in Sosci Survey  
product: Sosci Survey  
vulnerable version: <2.3.04a  
fixed version: 2.3.04a  
impact: Critical  
homepage: https://www.soscisurvey.de  
found: 2012-06-18  
by: T. Lazauninkas, V. Paulikas  
SEC Consult Vulnerability Lab  
https://www.sec-consult.com  
=======================================================================  
  
Vendor description:  
-------------------  
SoSci Survey provides a non-comercial survey service, letting anyone to create and  
share surveys for collecting data in a purpose of scientific research. It is a  
flexible and efficient tool as it lets you to create a very customizable survey,  
including active content (javascript) and PHP code.  
  
https://www.soscisurvey.de/  
  
  
Vulnerability overview/description:  
-----------------------------------  
1) Authorization Issues  
The web application fails to validate authorization for  
certain requests. This allows unauthorized users to access private messages  
that belong to other users.  
  
2) Cross-Site Scripting  
The web application is prone to persistent and reflected Cross-Site Scripting  
attacks. The vulnerability can be used to include HTML or JavaScript  
code to the affected web page. The code is executed in the browser of  
users if they visit the manipulated site. The vulnerability can be used  
to change the contents of the displayed site, redirect to other sites  
or steal user credentials. Additionally, Portal users are potential  
victims of browser exploits and JavaScript Trojans.  
  
3) Remote command execution  
Due to insufficient input validation, the web application fails to properly  
filter dangerous PHP code passed from the user side. This leads to OS command  
execution with the privileges of the web server. By exploiting this  
vulnerability, an attacker can read/write files, open connections, etc. posing  
a critical security risk.  
  
  
Proof of concept:  
-----------------  
  
1) In the user profile, users are able to send and receive private messages to  
each other. This also includes the administrative users. By modifying one of the  
vulnerable script's parameters an attacker can read the messages of other users.  
A proof of concept is provided below:  
  
https://www.example.com/admin/index.php?o=account&a=message.reply&id=[msg_id]  
  
By iterating between the integer parameter's id value, an attacker is able to exploit  
this vulnerability.  
  
2) If an invalid id value is passed to the receiver.edit module, which is handled by  
the index.php script, its contents is reflected to the user without proper filtering.  
This leads to javascript execution in the web browser. This issue can be easily exploited  
by navigating to the folowing URL:  
  
  
https://www.example.com/admin/index.php?o=panel&a=receiver.edit&id=<script>alert(document.cookie)</script>  
  
An alert with the user's session cookie will be shown.  
  
Persistent Cross-Site scripting was identified in the private messaging module. It was  
discovered, that [subject, title, firstName, surname, content] parameters are  
vulnerable to persistent Cross-Site scripting as they are saved and later shown  
without proper filtering. A sample request is provided below:  
  
POST /admin/index.php HTTP/1.1  
Host: www.example.com  
[...]  
rec-name=some_name&subject=%3Cscript%3Ealert%28document.cookie%29%3C%2Fscript%3E  
&message=asd%3Cscript%3Ealert%28document.cookie%29%3C%2Fscript%3E&o=account  
&a=message.send&reference=  
  
Many parameters are vulnerable to reflected Cross-Site Scripting vulnerabilities:  
  
URL:  
https://www.example.com/admin/index.php  
  
Parameters:  
replace[0-24]  
search[0-24]  
id  
O  
Referer (header)  
  
URL:  
https://www.example.com/admin/ajax.feedback.php  
  
Parameters:  
dat_type  
  
3) When creating a new survey it is possible to include PHP code. Despite that the web  
application is filtering most of the dangerous PHP functions, that would allow to execute OS  
commands, it is still possible to execute arbitrary commands by using the provided code below:  
  
print `id`;  
  
The above code, when executed, prints out the system id of the current user. This could be further  
exploited by an attacker for accessing the local file system, creating malicious files, opening  
remote conections, etc.  
  
  
Vulnerable / tested versions:  
-----------------------------  
Pre-installed version of SoSci Survey, hosted on www.soscisurvey.de domain, was  
tested. It was not possible to determine an exact version of the installed software.  
  
  
Vendor contact timeline:  
------------------------  
2013-01-29: Contacted vendor through [email protected]  
2013-01-29: Initial vendor response - issues will be verified  
2013-03-29: Status request sent  
2013-03-29: Vendor response: Security update 2.3.04a is available  
2013-04-17: SEC Consult releases coordinated security advisory  
  
  
Solution:  
---------  
Update to version 2.3.04a.  
  
  
Workaround:  
-----------  
  
  
Advisory URL:  
-------------  
https://www.sec-consult.com/en/Vulnerability-Lab/Advisories.htm  
  
  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
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Office Vienna  
Mooslackengasse 17  
A-1190 Vienna  
Austria  
  
Tel.: +43 / 1 / 890 30 43 - 0  
Fax.: +43 / 1 / 890 30 43 - 25  
Mail: research at sec-consult dot com  
https://www.sec-consult.com  
  
EOF T. Lazauninkas, V. Paulikas / @2013  
  
  
`