Document Title:
===============
AEF CMS v1.0.9 - (PM) Persistent Cross Site Scripting Vulnerability


References (Source):
====================
https://www.vulnerability-lab.com/get_content.php?id=2123



Release Date:
=============
2018-02-18


Vulnerability Laboratory ID (VL-ID):
====================================
2123


Common Vulnerability Scoring System:
====================================
4.4


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


Current Estimated Price:
========================
1.000a! - 2.000a!


Product & Service Introduction:
===============================
AEFs full name is Advanced Electron Forum. This bulletin board software is free software. It is written 
in PHP and MySQL. AEF has a very simple and easy to use Administration Panel and installing this software 
is a piece of cake! You can install new themes, customize themes the way you want. The User Control Panel 
has a simple yet beautiful interface where users can set their preferences for the board. This Bulletin 
board or forum software has all the general features that a forum software should have.

(Copy of the Homepage: https://www.softaculous.com/apps/forums/AEF & http://www.anelectron.com/)


Abstract Advisory Information:
==============================
The vulnerability laboratory core research team discovered a persistent web vulnerability in the official Advanced Electron Forum v1.0.9 CMS.


Vulnerability Disclosure Timeline:
==================================
2018-02-20: Public Disclosure (Vulnerability Laboratory)



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


Affected Product(s):
====================

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


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


Authentication Type:
====================
Restricted authentication (user/moderator) - User privileges


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


Disclosure Type:
================
Independent Security Research


Technical Details & Description:
================================
A persistent cross site scripting vulnerability has been discovered in the official Advanced Electron Forums v1.0.9 Content Management System.
The vulnerability allows remote attackers to inject own malicious script code with persistent attack vector to the application-side of the service.

The persistent cross site vulnerability is located in the `FTP Link` element of the `Private Message` module. The editor of the private message 
module allows to insert links without sanitizing the content. Thus allows remote attackers to inject malicious script code payloads as private 
message to compromise user credentials or to persistent manipulate the affected modules context. The injection point is the editor ftp link 
element and the execution point occurs in the message body context on arrival. The request method to inject is post with restricted user 
privileges and the attack vector is located on the application-side.

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):
[+] Private Messages

Vulnerable Input(s):
[+] Ftp Link (Editor Element)


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


Manual steps to reproduce the vulnerability ...
1. Open the web-application and login as user
2. Move to the private message module
3. Open up the editor by composing a message
4. add some short text, save the entry as draft
5. Open the draft and insert a ftp link with a script code payload
6. Save the entry and deliver the message to another test user
Note: The message only needs to be watched to execute on arrival
7. The test user opens the private message module and the persistent script code executes in the message body context
8. Successful reproduce of the persistent vulnerability!


PoC: Payload (Ftplink)
%0D%0A%0D%0A  or %0D%0A%0D%0A%0D%0A%0D%0A+


PoC: Vulnerable Source
<textarea name="pmbody" rows="13" cols="65" id="pmbody" onchange="storeCaret(this);" onkeyup="storeCaret(this);" 
onclick="storeCaret(this);" onselect="storeCaret(this);" style="visibility: visible; width: 487px; 
height: 226px;">This+is+a+private+test+message+with+payload+in+the+ftp+link%0D%0A%0D%0A</textarea>


PoC: Session Logs (Send Private Message)
Status: 200[OK]
POST https://aeforums.localhost:8000/AEF/index.php?act=usercp&ucpact=sendsaved&pmid=1 
  Mime Type[text/html]
   Request Header:
      Host[aeforums.localhost:8000]
      User-Agent[Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:56.0) Gecko/20100101 Firefox/56.0]
      Accept[text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8]
      Content-Type[application/x-www-form-urlencoded]
      Content-Length[174]
      Referer[https://aeforums.localhost:8000/AEF/index.php?act=usercp&ucpact=sendsaved&pmid=1]
      Cookie[AEFCookies1526[aefsid]=jmik0sqtslneqffjl537i931brqh3tzr; AEFCookies8381[aefsid]=x1m0rs9lhcl6hl3tbq7qbdh9jn0xsnsf]
      Connection[keep-alive]
      Upgrade-Insecure-Requests[1]
   POST-Daten:
      pmrecipients[admin]
      pmsubject[test]
      pmbody[This+is+a+private+test+message+with+payload+in+the+ftp+link%0D%0A%0D%0A]
      postcode[yerudyyk4joz8ea5]
      pmsaveinsentitems[on]
      sendpm[Send+PM]
   Response Header:
      Server[Apache]
      X-Powered-By[PHP/5.4.45]
      Content-Length[217]
      Content-Type[text/html; charset=ISO-8859-1]
-
Status: 200[OK]
GET https://aeforums.localhost:8000/AEF/evil.source 
  Mime Type[text/html]
   Request Header:
      Host[aeforums.localhost:8000]
      User-Agent[Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:56.0) Gecko/20100101 Firefox/56.0]
      Accept[text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8]
      Referer[https://aeforums.localhost:8000/AEF/index.php?act=usercp&ucpact=sendsaved&pmid=1]
      Cookie[AEFCookies1526[aefsid]=jmik0sqtslneqffjl537i931brqh3tzr; AEFCookies8381[aefsid]=x1m0rs9lhcl6hl3tbq7qbdh9jn0xsnsf]
      Connection[keep-alive]
      Upgrade-Insecure-Requests[1]
   Response Header:
      Server[Apache]
      Accept-Ranges[bytes]
      Content-Length[431]
      Content-Type[text/html; charset=UTF-8]


Reference(s):
https://aeforums.localhost:8000/AEF/
https://aeforums.localhost:8000/AEF/index.php


Solution - Fix & Patch:
=======================
The security vulnerability can be patched by a sanitize of the ftp link element input field in the private message module.
Parse in the editor the output location for the link to prevent the execution point of the issue. 


Security Risk:
==============
The security risk of the persistent cross site scripting web vulnerability in the open-source web-application is estimated as medium (cvss 4.4).


Credits & Authors:
==================
Benjamin K.M. [research@vulnerability-lab.com] - https://www.vulnerability-lab.com/show.php?user=Benjamin+K.M.


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=========================
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