Apache mod_isapi Dangling Pointer Vulnerability - Security Advisory - 
SOS-10-002

Release Date.                  5-Mar-2010
Last Update.                   -
Vendor Notification Date.      9-Feb-2010
Product.                       Apache HTTP Server
Platform.                      Microsoft Windows
Affected versions.             2.2.14 verified and
                               possibly others.
Severity Rating.               High
Impact.                        System access
Attack Vector.                 Remote
Solution Status.               Upgrade to 2.2.15 (as advised by
                               Apache)
CVE reference.                 CVE-2010-0425

Details.
The Apache HTTP Server, commonly referred to as Apache, is a
popular open source web server software. mod_isapi is a core
module of the Apache package that implements the Internet Server
extension API. The extension allows Apache to serve Internet
Server extensions (ISAPI .dll modules) for Microsoft Windows
based hosts.

By sending a specially crafted request followed by a reset packet
it is possible to trigger a vulnerability in Apache mod_isapi
that will unload the target ISAPI module from memory. However
function pointers still remain in memory and are called when
published ISAPI functions are referenced. This results in a
dangling pointer vulnerability.

Successful exploitation results in the execution of arbitrary
code with SYSTEM privileges.

Proof of Concept.
Proof of concept code is available for this vulnerability. The
payload will write a text file (sos.txt) to the Apache working
directory demonstrating that code execution is possible. The
code can be downloaded from the following link:

http://www.senseofsecurity.com.au/advisories/SOS-10-002-pwn-isapi.cpp

Furthermore, a video demonstrating the exploitation of this
vulnerability using a bind shell has been created. It can be viewed at the 
following link:
http://www.senseofsecurity.com.au/movies/SOS-10-002-apache-isapi.mp4

Solution.
Upgrade to the latest version of Apache HTTP Server (currently
2.2.15).

Discovered by.
Brett Gervasoni from Sense of Security Labs.

About us.

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The latest version of this advisory can be found at:

http://www.senseofsecurity.com.au/advisories/SOS-10-002