-----BEGIN PGP SIGNED MESSAGE-----

===========================================================================
             AUSCERT External Security Bulletin Redistribution

           ESB-2002.699 -- Microsoft Security Bulletin MS02-071
     Flaw in Windows WM_TIMER Message Handling Could Enable Privilege
                            Elevation (328310)
                             13 December 2002

===========================================================================

        AusCERT Security Bulletin Summary
        ---------------------------------

Product:                Windows NT 4.0
                        Windows NT 4.0, Terminal Server
                        Windows 2000
                        Windows XP
Vendor:                 Microsoft
Platform:               i386
                        IA-64
Impact:                 Administrator Compromise
Access Required:        Existing Account

- --------------------------BEGIN INCLUDED TEXT--------------------

- -----BEGIN PGP SIGNED MESSAGE-----

- - ----------------------------------------------------------------------
Title:      Flaw in Windows WM_TIMER Message Handling Could Enable
            Privilege Elevation (328310)
Date:       11 December 2002
Software:   Microsoft Windows NT 4.0, Windows 2000, and Windows XP
Impact:     Privilege elevation 
Max Risk:   Important
Bulletin:   MS02-071

Microsoft encourages customers to review the Security Bulletins at: 
http://www.microsoft.com/technet/security/bulletin/MS02-071.asp
http://www.microsoft.com/security/security_bulletins/ms02-071.asp 
- - ----------------------------------------------------------------------

Issue:
======
Windows messages provide a way for interactive processes to react
to user events (e.g., keystrokes or mouse movements) and communicate
with other interactive processes. One such message, WM_TIMER, is sent
at the expiration of a timer, and can be used to cause a process to
execute a timer callback function. A security vulnerability results
because it's possible for one process in the interactive desktop to
use a WM_TIMER message to cause another process to execute a callback
function at the address of its choice, even if the second process
did not set a timer. If that second process had higher privileges
than the first, this would provide the first process with a way of
exercising them. 

By default, several of the processes running in the interactive
desktop do so with LocalSystem privileges. As a result, an attacker
who had the ability to log onto a system interactively could
potentially run a program that would levy a WM_TIMER request upon
such a process, causing it to take any action the attacker
specified. This would give the attacker complete control over the
system. 

In addition to addressing this vulnerability, the patch also makes
changes to several processes that run on the interactive desktop
with high privileges. Although none of these would, in the
absence of the TM_TIMER vulnerability, enable an attacker to gain
privileges on the system, we have included them in the patch to
make the services more robust. 

Mitigating Factors:
====================
 - An attacker would need valid logon credentials to exploit the
   vulnerability. It could not be exploited remotely. 

 - Properly secured servers would be at little risk from this
   vulnerability. Standard best practices recommend only allowing
   trusted administrators to log onto such systems interactively;
   without such privileges, an attacker could not exploit the
   vulnerability. 

Risk Rating:
============
 - Important

Patch Availability:
===================
 - A patch is available to fix this vulnerability. Please read the 
   Security Bulletin at
   http://www.microsoft.com/technet/security/bulletin/ms02-071.asp
   for information on obtaining this patch.

- - ---------------------------------------------------------------------

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.

- -----BEGIN PGP SIGNATURE-----
Version: PGP 7.1

iQEVAwUBPfeeVY0ZSRQxA/UrAQGABAf/bCIkmCHDO/CstY9lrG1pgOKb/cvnEKfm
QDv4vWlqQz1WDvGVq1x+OpkGwNrqiyNTWb5JaJ8CxYyzmLHPGki5hesptuzvJomz
zuupTOWarpayMxR1NIqrAaX4xV7C4BZgt/BhuCexD36kG2Bt3DQ1pBEZdso9brOX
C02Xs4IP548Qdxg4cEuId35/WLALG4eWdCXaIZ4x2iNTUcOXxTM64weutXr4ZOtX
MPTzimuv4Z3ayT8RxBlvdRn9eBcpGcsUmTh2Cc8MKHdks12fzYZLxE4j7W9HzZp8
9Vso+ia97WG6tZm1PQXk+SPzsYXxQjfgYqgYCN+2DN9InXoYfqvJug==
=J48t
- -----END PGP SIGNATURE-----

- --------------------------END INCLUDED TEXT--------------------

You have received this e-mail bulletin as a result of your organisation's
registration with AusCERT. The mailing list you are subscribed to is
maintained within your organisation, so if you do not wish to continue
receiving these bulletins you should contact your local IT manager. If
you do not know who that is, please send an email to auscert@auscert.org.au
and we will forward your request to the appropriate person.

This security bulletin is provided as a service to AusCERT's members.  As
AusCERT did not write the document quoted above, AusCERT has had no control
over its content.  The decision to use any or all of this information is
the responsibility of each user or organisation, and should be done so in
accordance with site policies and procedures.

NOTE: This is only the original release of the security bulletin.  It may
not be updated when updates to the original are made.  If downloading at
a later date, it is recommended that the bulletin is retrieved directly
from the author\'s website to ensure that the information is still current.

Contact information for the authors of the original document is included
in the Security Bulletin above.  If you have any questions or need further
information, please contact them directly.

Previous advisories and external security bulletins can be retrieved from:

        http://www.auscert.org.au/render.html?cid=1980

If you believe that your system has been compromised, contact AusCERT or
your representative in FIRST (Forum of Incident Response and Security
Teams).

Internet Email: auscert@auscert.org.au
Facsimile:      (07) 3365 7031
Telephone:      (07) 3365 4417 (International: +61 7 3365 4417)
                AusCERT personnel answer during Queensland business 
                hours which are GMT+10:00 (AEST).  On call after hours 
                for member emergencies only.

-----BEGIN PGP SIGNATURE-----
Version: 2.6.3i
Charset: noconv
Comment: http://www.auscert.org.au/render.html?it=1967

iQCVAwUBPfnY4Ch9+71yA2DNAQF+GgP7B0GJfCtVpDEs+hkfOujmh+xam+jAEE0M
ZHEJSpPG9G9zif6vaoYvqCbnDu16Dh5h6EsnU8CtHKXpRbHlSjPecAxUO9kC469m
CmBcqOXpCEf6NYvOoJwlzMkeAbi0jloLeQ8pFeU92/DjgDBxbdBIRB3KdH5b26rp
o7gEHkwitUE=
=C8FO
-----END PGP SIGNATURE-----