[TSI-ADV-1201] Path Traversal on Polycom Web Management Interface

[Joao Paulo Caldas Campello <joao.paulo@xxxxxxxxxxxxxx>]

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=====[ Tempest Security Intelligence - Advisory #01 / 2012 ]============
 
     Path Traversal on Polycom Web Management Interface
     --------------------------------------------------

Authors:
    - Heyder Andrade:
        - @heyderandrade
        - http://linkedin.com/in/heyderandrade
        - < heyder.andrade[at]tempest[dot]com[dot]br >
    - Joao Paulo Caldas Campello:
        - @jpcampello
        - http://linkedin.com/in/jpcampello
        - < joao.paulo[at]tempest[dot]com[dot]br >

    Tempest Security Intelligence - Recife, Pernambuco - Brazil 
 
=====[ Table of Contents ]==============================================

 1. Overview
 2. Detailed description
 3. Aggravating factors
 4. Affected versions & Solutions
 5. Timeline of disclosure 
 6. Thanks & Acknowledgements
 7. References

=====[ Overview ]=======================================================
 
 * System affected  : Polycom Web Management Interface
 * Model            : G3/HDX 8000 HD
                      
 * Software Version : Durango 2.6.0 Release - build #4740
 * Embedded Linux   : Polycom Linux Development Platform v2.14.g3

                      Other versions or models may also be affected.
                      
 * Impact           : Successful exploitation of this vulnerability may
                      allow an attacker to view content of any arbitrary
                      file on Polycom operating system.

The Polycom HDX 8000 series [1] is a well-known video and audio 
conference device running an embedded Linux PPC system.

This advisory is also available at:

 - http://www.tempest.com.br/advisories/tsi-adv-1201/
 
=====[ Detailed description ]===========================================

The web management interface on the Polycom device allows users to
download two log files ("system log" and "error log"). This feature is
available through the following menus:

    Diagnostics --> System Log --> Download Logs

The access to these log files is provided by the script "a_getlog.cgi",
which receives the name of the log file ("messages" or "error") to be
downloaded through URL parameter "name", as shown on the above URL:

    - http://<affected_device>/a_getlog.cgi?name=messages

The Path Traversal vulnerability occurs due to lack of proper input
validation on user supplied data.

This vulnerability allows the attacker to navigate in the directory
structure, thus enabling access to arbitrary files in Polycom's
operating system.

As a proof-of-concept, it's possible to download "/etc/passwd" file
accessing the following URL:

    - http://<affected_device>/a_getlog.cgi?name=../../../etc/passwd

To fix this vulnerability, Polycom Web Management Interface should
perform proper input validation, sanitizing all user supplied data
before it's used elsewhere on the web application or in the
underlying operating system.

Also, Polycom Web Management Interface should not allow itself to be
accessed without proper configuration of a strong administrative
password.

=====[ Aggravating factors ]============================================

During system lab testing the following aggravating factors were
observed:

    01. The default administrative password of Polycom Web Management
        Interface was empty.

    02. The embedded web server (lighttpd) was running with superuser
        privileges, allowing access to any arbitrary files on the
        filesystem.

=====[ Affected versions & Solutions ]==================================

According to vendor's response, Polycom will publish Technical Bulletin
85802 to its costumers, reporting their official solution and mitigation
information.

They have also informed that this vulnerability affects the following
products:

 - Polycom HDX Video End Points running software version 2.6 and
   earlier.

Customers can download version 3.0 and newer at the link provided below:

 - 
http://support.polycom.com/PolycomService/support/us/support/video/hdx_series/

For customers who cannot update to version 3.0, Polycom recommends
sysadmins to disable the option for web management on HDX units running
versions 2.6 and older.

=====[ Timeline of disclosure  ]========================================

 - Dec/02/2011: Vendor contacted by e-mail on
                <security[at]polycom[dot]com >.

 - Dec/02/2011: Vendor first response.

 - Dec/28/2011: We have sent another e-mail asking for information.

 - Feb/15/2012: As vendor did not reply to our previous message, we have
                sent another e-mail telling we were going to disclose
                the advisories.

 - Feb/15/2012: Vendor responded asking for some more time to verify
                appropriate fixes and mitigations to vulnerabilities.

                We have agreed on releasing the advisories on two weeks.

 - Feb/29/2012: Vendor sent an email reporting the technical bulletins
                which describe their official solution and mitigation
                information they were going to provide to their
                costumers.

 - Mar/01/2012: Tempest and Polycom have coordinated publication date on
                March 05.

 - Mar/05/2012: Public disclosure of advisories.

=====[ Thanks & Acknowledgements ]======================================
 
 - Tempest Security Intelligence / Tempest's Pentest Team [2]
 - Evandro Hora < evandro[at]tempest[dot]com[dot].br >
 - Joaquim Brasil < joaquim.brasil[at]tempest[dot]com[dot].br >
 - Ricardo Ulisses < ricardo[at]tempest[dot]com[dot].br >
 
=====[ References ]=====================================================
 
 [1] http://www.polycom.com/
 [2] http://www.tempest.com.br/
 
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