SEC Consult Vulnerability Lab Security Advisory < 20121203-0 >
=======================================================================
              title: Unauthenticated local file inclusion
            product: F5 FirePass SSL VPN
 vulnerable version: <= 7.0.0  HF-70-6
      fixed version: 7.0.0 HF-70-7
             impact: Critical
           homepage: http://www.f5.com
              found: 2012-06-01
                 by: S. Viehböck
                     SEC Consult Vulnerability Lab
                     https://www.sec-consult.com
=======================================================================

Vendor/product description:
-----------------------------
"The FirePass SSL VPN" available as an appliance and in a Virtual
Edition provide security, flexibility, and ease of use. It grants access to
corporate applications using a technology that everyone understands: a web
browser. Users can have secure access from anywhere they have an Internet
connection, while FirePass ensures that connected computers are fully patched
and protected."

"FirePass provides robust, secure SSL VPN remote access to business
applications from a wide range of client devices, including Apple iPhone and
Windows Mobile devices.  Using full-tunnel SSL technology and client access
policies defined by system administrators, remote clients can log on to
corporate business applications under pre-defined access permissions and
client directory control."

URL: http://www.f5.com/products/firepass/


Vulnerability overview/description:
-----------------------------------
Due to insufficient input validation, an unauthenticated attacker can disclose
arbitrary local files with the privileges of the webserver. This includes the
user/administrator database. As the attacker-controlled path is passed to the 
PHP include() function, code execution is also possible.
Furthermore, the path is then passed to the unlink() function and therefore can
be used to delete arbitrary files in the filesystem which causes denial of
service.
As opposed to some information on the Internet (e.g.
https://twitter.com/FirePassHF/status/218886584672587776), it is not necessary
to have Citrix functionality enabled in order to exploit this vulnerability.


Proof of concept:
-----------------
The flaw exists in the CitrixAuth.php script in the parameter "sessionId".

An attacker can traverse directories with '../' and terminate the path with a
NULL byte.

The following exploit shows how files can be extracted from the file system:

POST /CitrixAuth.php HTTP/1.1
Host: hostname
Content-Type: application/none
Content-Length: 68

<sessionId>../../../../../etc/passwd </sessionId>
                                  -> <- NULL byte


Vulnerable / tested versions:
-----------------------------
The vulnerability has been verified to exist in the Firepass SSL VPN version
7.0.0, which was the most recent version at the time of discovery.


Vendor contact timeline:
------------------------
2012-06-05: Contacting vendor security team via email.
2012-06-07: Response from vendor.
2012-06-12: Coordination call with vendor.
2012-06-14: Sent proof of concept exploit via encrypted channel.
2012 June:  Vendor releases HF-388207-1 and informs that solution (=advisory)
            will be published soon.
2012-08-22: Requesting status of solution.
2012-08-22: Vendor responds that solution will be published soon.
2012-10-23: Requesting status of solution.
2012-10-23: Vendor responds that something went wrong and they will look
            into it.
2012-11-07: Requesting status of solution.
2012-11-29: Vendor publishes SOL14046.
2012-12-03: Public release of SEC Consult advisory.



Solution:
---------
Apply HF-70-7 or HF-388207-1. For detailed information see:
http://support.f5.com/kb/en-us/solutions/public/14000/000/sol14046.html

Patch information is also available at:
http://support.f5.com/kb/en-us/solutions/public/13000/800/sol13826.html


Workaround:
-----------
No workaround available.


Advisory URL:
--------------
https://www.sec-consult.com/en/Vulnerability-Lab/Advisories.htm


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EOF S. Viehböck / @2012