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===========================================================================
             AUSCERT External Security Bulletin Redistribution

           ESB-2001.192 -- Microsoft Security Bulletin MS01-024
    Malformed Request to Domain Controller can Cause Memory Exhaustion
                                10 May 2001

===========================================================================

        AusCERT Security Bulletin Summary
        ---------------------------------

Product:                Microsoft Windows domain controllers
Vendor:                 Microsoft
Operating System:       Microsoft Windows 2000 Server 
                        Microsoft Windows 2000 Advanced Server
                        Microsoft Windows 2000 Datacenter Server
Impact:                 Denial of Service
Access Required:        Remote

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- - ---------------------------------------------------------------------
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.

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