__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Flaw in Windows WM_TIMER Message Handling [Microsoft Security Bulletin MS02-071] December 13, 2002 14:00 GMT Number N-027 ______________________________________________________________________________ PROBLEM: 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. PLATFORM: Microsoft Windows NT 4.0 Microsoft Windows NT 4.0, Terminal Server Edition Microsoft Windows 2000 Microsoft Windows XP DAMAGE: Once an attacker has access to the system, exploiting this vulnerability could give the attacker complete control. SOLUTION: Apply available patch ______________________________________________________________________________ VULNERABILITY The risk is MEDIUM. An attacker would need valid logon ASSESSMENT: credentials to exploit the vulnerability. It could not be exploited remotely. ______________________________________________________________________________ LINKS: CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/n-027.shtml ORIGINAL BULLETIN: http://www.microsoft.com/security/security_bulletins/ ms02-071.asp ______________________________________________________________________________ [***** Start Microsoft Security Bulletin MS02-071 *****] Microsoft Security Bulletin MS02-071 Flaw in Windows WM_TIMER Message Handling Could Enable Privilege Elevation (328310) Originally posted: December 11, 2002 Summary Who should read this bulletin: Customers using Microsoft® Windows® NT 4.0, Windows 2000, and Windows XP. Impact of vulnerability: Privilege elevation Maximum Severity Rating: Important Recommendation: Customers should install the patch at the earliest opportunity. Affected Software: Microsoft Windows NT 4.0 Microsoft Windows NT 4.0, Terminal Server Edition Microsoft Windows 2000 Microsoft Windows XP End User Bulletin: An end user version of this bulletin is available at: http://www.microsoft.com/security/security_bulletins/ms02-071.asp. Technical details Technical description: 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. Severity Rating: Windows NT 4.0 Important Windows NT 4.0, Terminal Server Edition Important Windows 2000 Important Windows XP Important The above assessment is based on the types of systems affected by the vulnerability, their typical deployment patterns, and the effect that exploiting the vulnerability would have on them. Vulnerability identifier: CAN-2002-1230 Tested Versions: Microsoft tested Windows NT 4.0, Windows NT 4.0, Terminal Server Edition, Windows 2000, and Windows XP to assess whether they are affected by these vulnerabilities. Previous versions are no longer supported, and may or may not be affected by these vulnerabilities. Patch availability Download locations for this patch Windows NT 4.0: All except Japanese NEC and Chinese - Hong Kong Japanese NEC Chinese - Hong Kong Windows NT 4.0, Terminal Server Edition: All Windows 2000: All except Japanese NEC Japanese NEC Windows XP: 32-bit Edition 64-bit Edition Additional information about this patch Installation platforms: The Windows NT 4.0 patch can be installed on systems running Service Pack 6a. The Windows NT 4.0, Terminal Server Edition patch can be installed on systems running Windows NT 4.0, Terminal Server Edition Service Pack 6. The Windows 2000 patch can be installed on systems running Windows 2000 Service Pack 1, Service Pack 2, or Service Pack 3. The patch for Windows XP can be installed on systems running Windows XP Gold or Service Pack 1. Inclusion in future service packs: The fix for this issue will be included in Windows 2000 Service Pack 4 and Windows XP Service Pack 2. Reboot needed: Yes Patch can be uninstalled: Yes Superseded patches: None. Verifying patch installation: Windows NT 4.0: To verify that the patch has been installed on the machine, confirm that all files listed in the file manifest in Knowledge Base article 328310 are present on the system. Windows NT 4.0 Terminal Server Edition: To verify that the patch has been installed on the machine, confirm that all files listed in the file manifest in Knowledge Base article 328310 are present on the system. Windows 2000: To verify that the patch has been installed on the machine, confirm that the following registry key has been created on the machine: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Updates\Windows 2000\SP4\Q328310. To verify the individual files, use the date/time and version information provided in the following registry key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Updates\Windows 2000\SP4\Q328310\Filelist. Windows XP: To verify that the patch has been installed, confirm that the following registry key has been created on the machine: HKLM\Software\Microsoft\Updates\Windows XP\SP2\Q328310. To verify the individual files, use the date/time and version information provided in the following registry key: HKLM\Software\Microsoft\Updates\Windows XP\SP2\Q328310\Filelist. Caveats: None Localization: Localized versions of this patch are available at the locations discussed in “Patch Availability”. Obtaining other security patches: Patches for other security issues are available from the following locations: Security patches are available from the Microsoft Download Center, and can be most easily found by doing a keyword search for "security_patch". Patches for consumer platforms are available from the WindowsUpdate web site Other information: Support: Microsoft Knowledge Base article 328310 discusses this issue and will be available approximately 24 hours after the release of this bulletin. Knowledge Base articles can be found on the Microsoft Online Support web site. Technical support is available from Microsoft Product Support Services. There is no charge for support calls associated with security patches. Security Resources: The Microsoft TechNet Security Web Site provides additional information about security in Microsoft products. Disclaimer: 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. Revisions: V1.0 (December 11, 2002): Bulletin Created. [***** End Microsoft Security Bulletin MS02-071 *****] _______________________________________________________________________________ CIAC wishes to acknowledge the contributions of Microsoft for the information contained in this bulletin. _______________________________________________________________________________ CIAC, the Computer Incident Advisory Capability, is the computer security incident response team for the U.S. Department of Energy (DOE) and the emergency backup response team for the National Institutes of Health (NIH). CIAC is located at the Lawrence Livermore National Laboratory in Livermore, California. CIAC is also a founding member of FIRST, the Forum of Incident Response and Security Teams, a global organization established to foster cooperation and coordination among computer security teams worldwide. CIAC services are available to DOE, DOE contractors, and the NIH. CIAC can be contacted at: Voice: +1 925-422-8193 (7x24) FAX: +1 925-423-8002 STU-III: +1 925-423-2604 E-mail: ciac@ciac.org Previous CIAC notices, anti-virus software, and other information are available from the CIAC Computer Security Archive. World Wide Web: http://www.ciac.org/ Anonymous FTP: ftp.ciac.org PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing communities receive CIAC bulletins. If you are not part of these communities, please contact your agency's response team to report incidents. Your agency's team will coordinate with CIAC. The Forum of Incident Response and Security Teams (FIRST) is a world-wide organization. A list of FIRST member organizations and their constituencies can be obtained via WWW at http://www.first.org/. This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes. 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