TCExam 11.3.007 Cross Site Scripting

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| TCExam Edit Cross-Site Scripting |  
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Summary  
=======  
  
TCExam 11.3.007 is subject to a cross-site scripting vulnerability. A  
'question_subject_id' parameter is not sufficiently sanitised before being  
written to the tce_edit_answer.php page. An attacker could distribute a  
malicious URL to specific users as part of a spear-phishing campaign. Users  
following the link would trigger this vulnerability which could potentially  
steal session cookies, redirect the user to a malicious URL or download  
malware onto their machine.  
  
CVE number: CVE-2012-4238  
Impact: Medium  
Vendor homepage: http://www.tcexam.org/  
Vendor notified: 06/08/2012  
Vendor fixed: 06/08/2012  
Credit: Chris Cooper of Reaction Information Security  
(http://www.reactionis.co.uk/)  
  
This advisory is posted at:  
  
http://www.reactionpenetrationtesting.co.uk/tcexam-cross-site-scripting.html  
  
  
Affected Products  
======== ========  
  
Confirmed in TCExam 11.3.007. Prior versions may also be affected.  
  
  
Details  
=======  
  
The question_subject_id parameter on the tce_edit_answer.php page was found  
to be subject to a cross-site scripting vulnerability. It was possible to  
inject arbitrary Javascript code into the parameter which is passed into the  
page content without sanitisation.   
  
The fact that the user must be authenticated as well as an administrator  
(permission level 5 or above) reduces the likelihood of a successful attack.  
However, the vulnerability could potentially be leveraged in a spear  
phishing attack, targeted at exam authors and administrators, to hijack  
their sessions.  
  
  
Impact  
======  
  
An attacker might entice users to follow a malicious URL, causing Javascript  
code to execute in their browser, potentially stealing session cookies,  
redirecting the user to a malicious URL or downloading malware onto their  
machine.  
  
  
Proof of Concept  
===== == =======  
  
Injecting the following Javascript code into a generic parameter on the  
calendar page will trigger the vulnerability, causing the page to return a  
Javascript alert box.  
  
"><script>alert(String.fromCharCode(120,115,115,116,101,115,116))</script>  
  
---  
Example 1 Request:  
+-----------------  
  
GET  
/TCExam/admin/code/tce_edit_answer.php?subject_module_id=2&question_subject_  
id=1"><script>alert(String.fromCharCode(120,115,115,116,101,115,116))</scrip  
t>&answer_question_id=7 HTTP/1.1  
Host: 192.168.0.6  
Referer: http://192.168.0.6/TCExam/admin/code/tce_edit_question.php  
Cookie: PHPSESSID=db1fe2b665994ff76356e7a28abfa5df  
  
---  
Example 1 Response:  
+------------------  
  
--- SNIP ---  
<a  
href="tce_edit_question.php?subject_module_id=2&question_subject_id=1\">  
<script>alert(String.fromCharCode(120,115,115,116,101,115,116))</script>&amp  
;question_id=7" title="Question Management" class="xmlbutton">< Question  
Management</a></span>  
--- SNIP ---  
  
  
Solution  
========  
  
Upgrade to TCExam 11.3.008.  
  
  
Distribution  
============  
  
In addition to posting on the website, a text version of this notice has  
been posted to the following e-mail and Usenet news recipients.  
  
* bugtraq () securityfocus com  
* full-disclosure () lists grok org uk   
  
Future updates of this advisory, if any, will be placed on the ReactionIS  
corporate website, but may or may not be actively announced on mailing lists  
or newsgroups. Users concerned about this problem are encouraged to check  
the URL below for any updates:  
  
  
  
http://www.reactionpenetrationtesting.co.uk/tcexam-cross-site-scripting.html  
  
============================================================================  
==  
  
Reaction Information Security   
Lombard House Business Centre,  
Suite 117,  
12-17 Upper Bridge Street,  
Canterbury, Kent, CT1 2NF  
  
Phone: +44 (0)1227 785050  
Email: research () reactionis {dot} co {dot} uk  
Web: http://www.reactionpenetrationtesting.co.uk  
`