SEC Consult SA-20090525-4 :: SonicOS Format String Vulnerability

[Bernhard Mueller <research@xxxxxxxxxxxxxxx>]

SEC Consult Security Advisory < 20090525-4 >
==========================================================================
              title: SonicOS Format String Vulnerability
            program: SonicWALL Global VPN Client
 vulnerable version: PRO 4100 SonicOS 4.0.0.2-51e Standard and Enhanced
                     possibly other versions
           homepage: http://www.sonicwall.com
              found: October 2006
                 by: lofi42
     permanent link: https://www.sec-consult.com/advisories_e.html#a54
==========================================================================

Product description:
--------------------

SonicOS Enhanced (SonicOSe) is the latest version of SonicWALL's
powerful SonicOS operating system, designed for the next generation of
SonicWALL firewall/VPN appliances.


Vulnerability overview:
-----------------------

A format string vulnerability exists in the logfile parsing function of
SonicOS. An attacker could crash the system or execute arbitrary code by
injecting format string metacharacters into the logfile, if an
administrator subsequently uses the SonicOS GUI to view the log.


Proof of concept:
-----------------

There are multiple ways to inject format string characters into the
logs. The following methods can be used to test for the vulnerability:

1. CFS: Add ebay.com to your "Forbidden Domains" and access
http://www.ebay.com/%s%s%s%s%s%s/. 

2. GroupVPN: Establish an GroupVPN Tunnel and enter at the XAUTH
Username %s%s%s%s%s. 

3. Webfrontend: Enter at the Login Page of your SonicWALL as Username %s
%s%s%s%s. 


SEC Consult will not release code execution exploits for this
vulnerability to the public.



Vendor contact timeline:
------------------------

2006:       Vulnerability found
2006.10.25: Vulnerability first reported to vendor
2009.02.17: Vulnerability reported to vendor again
2009.03.16: Request for status update
2009.04.21: Request for status update
2009.05.25: Public Release


Patch:
------

SEC Consult was not able to get any vendor feedback on this issue. We
are currently not aware of a patch or workaround.


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EOF SEC Consult Vulnerability Lab / @2009