__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Center ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Microsoft Domain Controller Core Service Memory Leak [Microsoft Security Bulletin MS01-024] May 12, 2001 01:00 GMT Number L-079 ______________________________________________________________________________ PROBLEM: A Windows 2000 domain controller core service contains a memory leak, triggered when attempting to process a certain invalid service request. Repeatedly sending such a request could deplete the available memory on the server. PLATFORM: Microsoft Windows 2000 Server Microsoft Windows 2000 Advanced Server Microsoft Windows 2000 Datacenter Server DAMAGE: Temporary Denial of Service. Rebooting the affected system restores service. SOLUTION: Apply the patches described below. ______________________________________________________________________________ VULNERABILITY LOW. This is a temporary and partial denial of service of ASSESSMENT: attack, fixed by rebooting. It does not cause permanent damage to the domain controller. ______________________________________________________________________________ [****** Start Microsoft Advisory ******] - --------------------------------------------------------------------- Title: Malformed Request to Domain Controller can Cause Memory Exhaustion Date: 08 May 2001 Software: Windows 2000 Server Windows 2000 Advanced Server Windows 2000 Datacenter Server Impact: Denial of Service Bulletin: MS01-024 Microsoft encourages customers to review the Security Bulletin at: http://www.microsoft.com/technet/security/bulletin/MS01-024.asp. - ---------------------------------------------------------------------- Issue: ====== A core service running on all Windows 2000 domain controllers (but not on any other machines) contains a memory leak, which can be triggered when it attempts to process a certain type of invalid service request. By repeatedly sending such a request, an attacker could deplete the available memory on the server. If memory were sufficiently depleted, the domain controller could become unresponsive, which would prevent it from processing logon requests or issuing new Kerberos tickets. An affected machine could be put back into service by rebooting. Mitigating Factors: ==================== - Users who were already logged on and using previously issued Kerberos tickets would not be affected by domain controller unavailability. - If there were multiple domain controllers on the domain, the unaffected machines could pick up the other machine's load. - If normal security practices have been followed, Internet users would be prevented by firewalls and other measures from levying requests directly to domain controllers. Patch Availability: =================== - A patch is available to fix this vulnerability. Please read the Security Bulletin http://www.microsoft.com/technet/security/bulletin/ms01-024.asp for information on obtaining this patch. Acknowledgment: =============== - Peter Grundl of Defcom (www.defcom.com) ---------------------------------------------------------------------- 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. [****** End Microsoft Advisory ******] _______________________________________________________________________________ CIAC wishes to acknowledge the contributions of Microsoft for the information contained in this bulletin. _______________________________________________________________________________ CIAC, the Computer Incident Advisory Center, 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. 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