Path Traversal on Polycom Web Management Interface
Neste post reproduzimos um advisory (nota técnica) detalhando uma vulnerabilidade que descobrimos na interface web de gerenciamento em um dos produtos de teleconferência da Polycom. A vulnerabilidade viabiliza o acesso a quaisquer arquivos no filesystem do ativo afetado.
O advisory (em inglês) contendo os detalhes completos dessa vulnerabilidade está listado a seguir:
=====[ 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  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  - 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 ]===========================================================  http://www.polycom.com/  http://www.tempest.com.br/ ==============================================================================