REVISED: Microsoft Security Bulletin MS03-030: Unchecked Buffer in DirectX

Title: Unchecked Buffer in DirectX Could Enable System
Compromise (819696)
Released: 23 July 2003
Revised: 20 August 2003 (version 2.0)

Software: Microsoft DirectX(r) 5.2 on Windows 98
Microsoft DirectX 6.1 on Windows 98 SE
Microsoft DirectX 7.1 on Windows Millennium Edition
Microsoft DirectX 7.0 on Windows 2000
Microsoft DirectX 8.0, 8.0a, 8.1, 8.1a, and 8.1b when
installed on Windows 98, Windows 98 SE, Windows
Millennium Edition or Windows 2000
Microsoft DirectX 8.1 on Windows XP or
Windows Server 2003
Microsoft DirectX 9.0a when installed on Windows 98,
Windows 98 SE, Windows Millennium Edition (Windows Me),
Windows 2000, Windows XP, or Windows Server 2003
Microsoft Windows NT 4.0 Server with either Windows
Media Player 6.4 or Internet Explorer 6 Service Pack 1
installed.
Microsoft Windows NT 4.0, Terminal Server Edition with
either Windows Media Player 6.4 or Internet Explorer 6
Service Pack 1 installed.

Impact: Allow an attacker to execute code on a user's system
Max Risk: Critical
Bulletin: MS03-030

Microsoft encourages customers to review the Security Bulletin at:
http://www.microsoft.com/technet/security/bulletin/MS03-030.asp
http://www.microsoft.com/security/security_bulletins/MS03-030.asp
- ----------------------------------------------------------------------

Reason for Revision:
====================
Subsequent to the original release of this bulletin, customers
requested that we support additional versions of DirectX that were
not covered by the original patches. This bulletin has been updated
to provide information about this new patch.

Issue:
======
DirectX consists of a set of low-level Application Programming
Interfaces (APIs) that are used by Windows programs for multimedia
support. Within DirectX, the DirectShow technology performs client-
side audio and video sourcing, manipulation, and rendering.
There are two buffer overruns with identical effects in the
function used by DirectShow to check parameters in a Musical
Instrument Digital Interface (MIDI) file. A security vulnerability
results because it could be possible for a malicious user to
attempt to exploit these flaws and execute code in the security
context of the logged-on user.

An attacker could seek to exploit this vulnerability by creating a
specially crafted MIDI file designed to exploit this vulnerability
and then host it on a Web site or on a network share, or send it by
using an HTML-based e-mail. In the case where the file was hosted
on a Web site or network share, the user would need to open the
specially crafted file. If the file was embedded in a page the
vulnerability could be exploited when a user visited the Web page.
In the HTML-based e-mail case, the vulnerability could be exploited
when a user opened or previewed the HTML-based e-mail. A successful
attack could cause DirectShow, or an application making use of
DirectShow, to fail. A successful attack could also cause an
attacker's code to run on the user's computer in the security
context of the user.

Mitigating Factors:
====================
- - By default, Internet Explorer on Windows Server 2003 runs in
Enhanced Security Configuration. This default configuration of
Internet Explorer blocks the e-mail-based vector of this attack
because Microsoft Outlook Express running on Windows Server 2003 by
default reads e-mail in plain text. If Internet Explorer Enhanced
Security Configuration were disabled, the protections put in place
that prevent this vulnerability from being exploited would be
removed.
- - In the Web-based attack scenario, the attacker would have to host
a Web site that contained a Web page used to exploit these
vulnerabilities. An attacker would have no way to force users to
visit a malicious Web site outside the HTML-based e-mail vector.
Instead, the attacker would need to lure them there, typically by
getting them to click a link that would take them to the attacker's
site.
- - The combination of the above means that on Windows Server 2003 an
administrator browsing only to trusted sites should be safe from
this vulnerability.
- - Code executed on the system would only run under the privileges
of the logged-on user.

Risk Rating:
============
- - Critical

Patch Availability:
===================
- A patch is available to fix this vulnerability. Please read the
Security Bulletins at
http://www.microsoft.com/technet/security/bulletin/MS03-030.asp
http://www.microsoft.com/security/security_bulletins/MS03-30.asp
for information on obtaining this patch.

Acknowledgment:
===============
- - eEye Digital Security, http://www.eeye.com