__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Microsoft Unchecked Buffer in RAS Phonebook Vulnerability [Microsoft Security Bulletin MS02-029] June 13, 2002 19:00 GMT Number M-090 [Revised 21 June 2002] [Revised 3 July 2002] ______________________________________________________________________________ PROBLEM: A flaw exists in the Remote Access Service (RAS) phonebook implementation. The flaw is susceptible to a buffer overrun. PLATFORM: * Windows NT 4.0 * Windows NT 4.0 Terminal Server Edition * Windows 2000 * Windows XP * Microsoft Routing and Remote Access Server, which can be installed on Windows NT 4.0 Service Pack 6 or NT 4.0 Terminal Server Edition Service Pack 6. DAMAGE: Exploitation of this vulnerability can lead to either of two things: (1) Causing a system failure. (2) Running code on the system with LocalSystem privileges. SOLUTION: Apply appropriate patches as prescribed by Microsoft's security bulletin. ______________________________________________________________________________ VULNERABILITY The risk is MEDIUM. This is a local privilege elevation ASSESSMENT: vulnerability. A malicious user must have the ability to interactively log on to a system. An attacker who successfully exploited this vulnerability could gain complete control over the machine, thereby gaining the ability to take any desired action on the machine. ______________________________________________________________________________ LINKS: CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/m-090.shtml ORIGINAL BULLETIN: http://www.microsoft.com/technet/treeview/ default.asp?url=/technet/security/ bulletin/MS02-029.asp ______________________________________________________________________________ [***** Start Microsoft Security Bulletin MS02-029 *****] Microsoft Security Bulletin MS02-029 Unchecked Buffer in Remote Access Service Phonebook Could Lead to Code Execution (Q318138) Originally posted: June 12, 2002 Updated: July 2, 2002 (Version 2.0) Summary Who should read this bulletin: Customers using Microsoft® Windows NT®, Windows® 2000 and Windows XP. Impact of vulnerability: Local privilege elevation. Maximum Severity Rating: Critical Recommendation: Administrators should apply the patch to immediately to machines that allow unprivileged users to log onto them interactively such as workstations and Terminal Servers. Affected Software: * Microsoft Windows NT 4.0 * Microsoft Windows NT 4.0 Terminal Server Edition * Microsoft Windows 2000 * Microsoft Windows XP * Microsoft Routing and Remote Access Server, which can be installed on Windows NT 4.0 Service Pack 6 or NT 4.0 Terminal Server Edition Service Pack 6. Technical details Technical description: On June 12, 2002, Microsoft released the original version of this bulletin. On July 2, 2002, the bulletin was updated to reflect the availability of a revised patch. Although the original patch completely eliminated the vulnerability, it had the side effect of preventing non-administrative users from making VPN connections in some cases. The revised patch correctly handles VPN connections. The revised patch is immediately available from the Download Center and will be soon made available via WindowsUpdate. The Remote Access Service (RAS) provides dial-up connections between computers and networks over phone lines. RAS is delivered as a native system service in Windows NT 4.0, Windows 2000 and Windows XP, and also is included in a separately downloadable Routing and Remote Access Server (RRAS) for Windows NT 4.0. All of these implementations include a RAS phonebook, which is used to store information about telephone numbers, security, and network settings used to dial-up remote systems. A flaw exists in the RAS phonebook implementation: a phonebook value is not properly checked, and is susceptible to a buffer overrun. The overrun could be exploited for either of two purposes: causing a system failure, or running code on the system with LocalSystem privileges. If an attacker were able to log onto an affected server and modify a phonebook entry using specially malformed data, then made a connection using the modified phonebook entry, the specially malformed data could be run as code by the system. Mitigating factors: * The vulnerability could only be exploited by an attacker who had the appropriate credentials to log onto an affected system. * Best practices suggests that unprivileged users not be allowed to interactively log onto business-critical servers. If this recommendation has been followed machines such as domain controllers, ERP servers, print and file servers, database servers, and others would not be at risk from this vulnerability. Severity Rating: Internet Servers Intranet Servers Client Systems +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Windows NT 4.0 Low Low Moderate +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Windows NT 4.0 Routing and Remote Access Server Low Low Moderate +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Windows NT 4 Terminal Server Edition Low Critical None +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Windows NT 4 Terminal Server Edition, Routing and Remote Access Server Low Critical None +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Windows 2000 Low Critical Moderate +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Windows XP Low Low Moderate +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 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. The attacker must have credentials to logon to the computer where the RAS phonebook is held. Vulnerability identifier: CAN-2002-0366 Tested Versions: Microsoft tested Windows NT4.0, Windows NT 4.0 Terminal Server Edition, Windows 2000, and Windows XP to assess whether they are affected by this vulnerability. Previous versions are no longer supported, and may or may not be affected by these vulnerabilities. Patch availability Download locations for this patch * Microsoft Windows NT 4.0: http://www.microsoft.com/ntserver/nts/downloads/security/q318138/default.asp * Microsoft Windows NT 4.0 running RRAS (English Only): http://www.microsoft.com/ntserver/nts/downloads/security/q318138/default.asp * Microsoft Windows NT 4.0 Terminal Server Edition: http://www.microsoft.com/ntserver/terminalserver/downloads/security/q318138/default.asp * Microsoft Windows NT 4.0 Terminal Server Edition running RRAS (English Only): http://www.microsoft.com/ntserver/terminalserver/downloads/security/q318138/default.asp * Microsoft Windows 2000: http://www.microsoft.com/windows2000/downloads/security/q318138/default.asp * Microsoft Windows XP: http://www.microsoft.com/downloads/release.asp?ReleaseID=38833 * Microsoft Windows XP 64-bit Edition: http://www.microsoft.com/downloads/release.asp?ReleaseID=39011 Additional information about this patch Installation platforms: * The Windows NT 4.0 patch can be installed on systems running Service Pack 6a. * The Windows Routing and Remote Access Server patch can be installed on systems running Windows NT 4.0 Service Pack 6a (English only). * 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 NT 4.0 Terminal Server Edition, Routing and Remote Access Server 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 or Windows 2000 Service Pack 2. * The patch for Windows XP can be installed on systems running Windows XP Gold. Inclusion in future service packs: * The fix for this issue will be included in Windows 2000 Service Pack 3. * The fix for this issue will be included in Windows XP Service Pack 1. Reboot needed: Yes Superseded patches: None. Verifying patch installation: Windows NT 4.0 Service Pack 6a: * 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\Windows NT\CurrentVersion\Hotfix\Q318138 * To verify the individual files, consult the file manifest in Knowledge Base article Q318138. Windows NT 4.0 Terminal Server Edition Service Pack 6: * 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\Windows NT\CurrentVersion\Hotfix\Q318138 * To verify the individual files, consult the file manifest in Knowledge Base article Q318138. Windows 2000 Service Pack 2: * 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\SP3\Q318138 * 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\SP3\Q318138\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\SP1\Q318138 * To verify the individual files, use the date/time and version information provided in the following registry key: HKLM\Software\Microsoft\Updates\Windows XP\SP1\Q318138\Filelist Caveats: None Localization: Localized versions of this patch are currently available at the locations listed above 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 * All patches available via WindowsUpdate also are available in a redistributable form from the WindowsUpdate Corporate site. Other information: Acknowledgments Microsoft thanks Mark Litchfield of Next Generation Security Software Ltd. for reporting this issue to us and working with us to protect customers. Support: * Microsoft Knowledge Base article Q318138 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 (June 12, 2002): Bulletin Created. - V1.1 (June 20, 2002): Caveats section updated to include information regarding an issue with the patch and VPN connections. - V1.2 (July 1, 2002): Caveats section updated to clarify that the patch has been removed from WindowsUpdate. - V2.0 (July 2, 2002): Updated with revised patch that correctly handles VPN connections. [***** End Microsoft Security Bulletin MS02-029 *****] _______________________________________________________________________________ CIAC wishes to acknowledge the contributions of Microsoft Corporation 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. 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