Polycom Web Management Interface Directory Traversal

`=====[ 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/  
  
==============================================================================  
  
`