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Security Advisory – Apache 2.2.14 modisapi Dangling Pointer Vulnerability


Sense of Security – Security Advisory – SOS-10-002

Release Date. 5-Mar-2010
Last Update.
Vendor Notification Date. 9-Feb-2010
Product. Apache HTTP Server
Platform. 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



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:




Furthermore, a video demonstrating the exploitation of this vulnerability using a bind shell has been created.



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


Discovered by.

Brett Gervasoni from Sense of Security Labs. Brett is a member of Sense of Security’s award winning penetration test team.