Public Vulnerability Reports

NGSEC StackDefender 1.10 Invalid Pointer Dereference Vulnerability

08.03.04

BACKGROUND

StackDefender is an IPS (Intrusion Prevention System), for Win32
platforms, that will deny shellcode from executing in User Stack and
Writable memory regions. StackDefender uses PAX technology for this
purpose.

DESCRIPTION

StackDefender offers protection by forcing executables run on a
protected system to load StackDefender dll's. This is done by hooking
the ZwOpenFile and ZwCreateFile functions. These two kernel API's are
responsible opening and creating files. The ZwOpenFile and ZwCreateFile
function declarations are as follows:

NTSTATUS  ZwCreateFile(
OUT PHANDLE  FileHandle,
IN ACCESS_MASK  DesiredAccess,
IN POBJECT_ATTRIBUTES  ObjectAttributes,
OUT PIO_STATUS_BLOCK  IoStatusBlock,
IN PLARGE_INTEGER  AllocationSize  OPTIONAL,
IN ULONG  FileAttributes,
IN ULONG  ShareAccess,
IN ULONG  CreateDisposition,
IN ULONG  CreateOptions,
IN PVOID  EaBuffer  OPTIONAL,
IN ULONG  EaLength);

NTSTATUS  ZwOpenFile(
OUT PHANDLE  FileHandle,
IN ACCESS_MASK  DesiredAccess,
IN POBJECT_ATTRIBUTES  ObjectAttributes,
OUT PIO_STATUS_BLOCK  IoStatusBlock,
IN ULONG  ShareAccess,
IN ULONG  OpenOptions);

The problem specifically exists because StackDefender fails to verify
'ObjectAttribues' as a valid address prior accessing the structures
members.

ANALYSIS

Successful exploitation allows remote and local attackers to cause the
underlying system to crash. This is possible by specifying an invalid
address for 'ObjectAttribues'. Exploitation requires that an attacker
has an exploitation vector to the system that StackDefender attempts to
block.

DETECTION

iDEFENSE has confirmed the existence of this vulnerability in
StackDefender 1.10.

WORKAROUND

iDEFENSE is currently unaware of any workarounds for this issue.

VENDOR RESPONSE

The vendor has discontinued support for StackDefender 1.10 and has
recommended that all users still using StackDefender 1.10 upgrade to
StackDefender 2.10.

http://www.ngsec.com/downloads/stackdefender/StackDefender-2.10.exe

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2004-0767 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org), which standardizes names for
security problems.

DISCLOSURE TIMELINE

07/10/2004    Vulnerability discovered by iDEFENSE
07/12/2004    Initial vendor contact
07/22/2004    Initial vendor response
08/03/2004    Public disclosure

CREDIT

iDEFENSE Labs is credited with the discovery of this vulnerability.

Get paid for vulnerability research
http://www.idefense.com/poi/teams/vcp.jsp

LEGAL NOTICES

Copyright © 2004 Verisign, Inc.

Permission is granted for the redistribution of this alert
electronically. It may not be edited in any way without the express
written consent of iDEFENSE. If you wish to reprint the whole or any
part of this alert in any other medium other than electronically, please
email customerservice@idefense.com for permission.

Disclaimer: The information in the advisory is believed to be accurate
at the time of publishing based on currently available information. Use
of the information constitutes acceptance for use in an AS IS condition.
There are no warranties with regard to this information. Neither the
author nor the publisher accepts any liability for any direct, indirect,
or consequential loss or damage arising from use of, or reliance on,
this information.