Microsoft Security Bulletin MS02-071:Flaw in Windows WM_TIMER Message Handling Could Enable Privilege Elevation (328310)

2002-12-14T00:00:00
ID SECURITYVULNS:DOC:3871
Type securityvulns
Reporter Securityvulns
Modified 2002-12-14T00:00:00

Description

-----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-----


You have received this e-mail bulletin because of your subscription to the Microsoft Product Security Notification Service. For more information on this service, please visit http://www.microsoft.com/technet/security/notify.asp.

To verify the digital signature on this bulletin, please download our PGP key at http://www.microsoft.com/technet/security/notify.asp.

To unsubscribe from the Microsoft Security Notification Service, please visit the Microsoft Profile Center at http://register.microsoft.com/regsys/pic.asp

If you do not wish to use Microsoft Passport, you can unsubscribe from the Microsoft Security Notification Service via email as described below: Reply to this message with the word UNSUBSCRIBE in the Subject line.

For security-related information about Microsoft products, please visit the Microsoft Security Advisor web site at http://www.microsoft.com/security.