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-----BEGIN PGP SIGNED MESSAGE----- =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2002.164 -- Microsoft Security Bulletin MS02-017 Q311967: Unchecked buffer in the Multiple UNC Provider Could Enable File Execution 5 April 2002 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Multiple UNC Provider (MUP) Vendor: Microsoft Operating System: Windows NT 4.0 Workstation Windows NT 4.0 Server Windows NT 4.0 Server, Enterprise Edition Windows NT 4 Terminal Server Edition Windows 2000 Professional Windows 2000 Server Windows 2000 Advanced Server Windows XP Professional Impact: Increased Privileges Execute Arbitrary Code/Commands Access Required: Local - --------------------------BEGIN INCLUDED TEXT-------------------- Title: Q311967: Unchecked buffer in the Multiple UNC Provider Could Enable Code Execution Date: 04 April 2002 Software: - - Microsoft Windows NT 4.0 Workstation - - Microsoft Windows NT 4.0 Server - - Microsoft Windows NT 4.0 Server, Enterprise Edition - - Microsoft Windows NT 4 Terminal Server Edition - - Microsoft Windows 2000 Professional - - Microsoft Windows 2000 Server - - Microsoft Windows 2000 Advanced Server - - Microsoft Windows XP Professional Impact: Local privilege elevation and run code of attacker's choice. Recommendation: Administrators should consider applying the patch to machines that allow unprivileged users to log onto them interactively such as workstations and Terminal Servers. Max Risk: Moderate Bulletin: MS02-017 Microsoft encourages customers to review the Security Bulletin at: http://www.microsoft.com/technet/security/bulletin/MS02-017.asp. - - - ---------------------------------------------------------------------- Issue: ====== The Multiple UNC Provider (MUP) is a Windows service that assists in locating network resources that are identified via UNC (uniform naming convention). The MUP receives commands containing UNC names from applications and sends the name to each registered UNC provider, LAN Manager workstation, and any others that are installed. When a provider identifies a UNC name as its own, the MUP automatically redirects future instances of that name to that provider. When MUP requests a file using the uniform naming convention (UNC), it will allocate a buffer to store this request. There is proper input checking in this first buffer. However, MUP stores another copy of the file request in a buffer when it sends this request to a redirector. This second copy of the buffer does not check inputs correctly, thereby creating the possibility that a resource request to it from an unprivileged process could cause a buffer overrun. The overrun could be exploited for either of two purposes: causing a system failure, or running code on the system with Local System privileges. Mitigating Factors: ==================== The MUP request can only be levied by a process on the local system. As a result, the vulnerability could only be exploited by a user who could log onto an affected system interactively. On Windows 2000 systems, the vulnerability could not reliably be used to run code. This is because the attacker would need to know where the buffer was located in memory, but in Windows 2000 this is not externally discoverable or controllable. Best practices suggests that unprivileged users not be allow 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. Risk Rating: ============ - Internet systems: Low - Intranet systems: Moderate - Client systems: Moderate Patch Availability: =================== - A patch is available to fix this vulnerability. Please read the Security Bulletin at http://www.microsoft.com/technet/security/bulletin/ms02-017.asp for information on obtaining this patch. Acknowledgment: =============== - NSFOCUS at http://www.nsfocus.com - --------------------------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 original authors 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/Information/advisories.html 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). 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