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AUSCERT External Security Bulletin Redistribution
ESB-2002.276 -- Microsoft Security Bulletin MS02-022
Unchecked Buffer in MSN Chat Control Can Lead to Code Execution (Q321661)
12 June 2002
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: MSN Messenger 4.5
MSN Messenger 4.6
Exchange Instant Messenger 4.5
Exchange Instant Messenger 4.6
MSN Chat Control
Vendor: Microsoft
Operating System: Windows
Impact: Execute Arbitrary Code/Commands
Access Required: Remote
Ref: ESB-2002.218
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Title: Unchecked Buffer in MSN Chat Control Can Lead to Code
Execution (Q321661)
Released: 08 May 2002
Revised: 11 June 2002 (version 2.0)
Software: MSN Chat, MSN Messenger, Exchange Instant Messenger
Impact: Run Code of Attacker's Choice
Max Risk: Critical
Bulletin: MS02-022
Microsoft encourages customers to review the Security Bulletin at:
http://www.microsoft.com/technet/security/bulletin/MS02-022.asp.
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Reason for Revision:
====================
On May 8 2002, Microsoft released the original version of this
bulletin. On June 11, 2002 the bulletin was updated to announce
that while the fixes issued on May 8 2002 resolved the vulnerability,
they did not protect in all cases against the reintroduction of the
vulnerable control. As a result, a new set of fixes is being released
to ensure that systems are fully protected against the reintroduction
of the vulnerable control. A new MSN Chat control, updated patch,
updated version of MSN Messenger and an updated version of
Exchange Instant Messenger have been made available. Customers who
have applied any of the fixes released on May 8, 2002 are
encouraged to consider applying the updated fixes.
Issue:
======
The MSN Chat control is an ActiveX control that allows groups of
users to gather in a single, virtual location online to engage in
text messaging. The control is offered for download as a single
ActiveX control from a number of MSN sites. In addition, it is
included with MSN Messenger since version 4.5 and Exchange Instant
Messenger. While the MSN Chat control is included with these
products it is not used to provide Instant Messaging functionality,
but rather to add chat functionality to those products.
An unchecked buffer exists in one of the functions that handles
input parameters in the MSN Chat control. A security
vulnerability results because it is possible for a malicious user
to levy a buffer overrun attack and attempt to exploit this flaw.
A successful attack could allow code to run in the user's context.
It would be possible for an attacker to attempt to exploit
this vulnerability either through a malicious web site or through
HTML email. However, Outlook Express 6.0 and the
Outlook Email Security Update, which is available for
Outlook 98 and Outlook 2000, Outlook 2002 and can thwart such
attempts through their default security settings.
Mitigating Factors:
====================
- A successful attack would require that the user have installed
the MSN Chat control, MSN Messenger, or
Exchange Instant Messenger.
- The MSN Chat control does not install with any version of
Windows or Internet Explorer by default.
- Windows Messenger which ships with Windows XP does not
include the MSN Chat control. Windows XP users would be
vulnerable only if they have chosen to install the MSN Chat
control from MSN sites.
- The HTML email attack vector is blocked by the following
Microsoft mail products:
- Outlook 98 and Outlook 2000 with the
Outlook Email Security Update
- Outlook 2002
- Outlook Express.
This is because these products all open HTML email in the
Restricted Sites zone by default.
Risk Rating:
============
- Internet systems: Low
- Intranet systems: Low
- Client systems: Critical
Patch Availability:
===================
- A patch is available to fix this vulnerability. Please read the
Security Bulletin at
http://www.microsoft.com/technet/security/bulletin/ms02-022.asp
for information on obtaining this patch.
Acknowledgment:
===============
- eEye Digital Security (http://www.eeye.com)
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THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS
PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS
ALL
WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
IN NO EVENT
SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY
DAMAGES
WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL,
LOSS OF
BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR
ITS
SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME
STATES DO
NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL
OR
INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.
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