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The U.S. Department of Energy
Computer Incident Advisory Center
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INFORMATION BULLETIN
Microsoft Domain Controller Core Service Memory Leak
[Microsoft Security Bulletin MS01-024]
May 12, 2001 01:00 GMT Number L-079
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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.
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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.
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[****** 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)
----------------------------------------------------------------------
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DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING
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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.
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E-mail: ciac@ciac.org
Previous CIAC notices, anti-virus software, and other information are
available from the CIAC Computer Security Archive.
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PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing
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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
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