-----BEGIN PGP SIGNED MESSAGE-----

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

-----BEGIN PGP SIGNATURE-----
Version: PGP Personal Privacy 6.5.3

iQEVAwUBOvihFI0ZSRQxA/UrAQFjwQf9EzJuxHpAWeQMGI7THisUikF3KiJsT3KW
2ZfI9OFw0Av+p55OZqhly8kKo0k+JGKhztutIqXRVPJlzBnRe1lyW4sORTz+q6vH
zIpeT21QoLGHC55n9Hvdgezc742H7ZolGtu5Xlqk2+uQCaDlJuLXB7wh1t+hxC8H
EbXyy2xhlz3vpOVBTlo1sqzTVRGIMmVhcPuNM6uZpQwdovrsLN/2RUJjJYd8o5v1
8E1/pIAS81bg50seLjXcOXVgEIzJZptKnHFcNuoR/Ly72/DmWqGcu/HOkqFz1B7Q
JKpeZ/8KkYzyopKycIdOD77uEsaaRxUdkrius0bVvkdy592wzCSUyA==
=5uEI
-----END PGP SIGNATURE-----

   *******************************************************************
You have received  this e-mail bulletin as a result  of your registration
to  the   Microsoft  Product  Security  Notification   Service.  You  may
unsubscribe from this e-mail notification  service at any time by sending
an  e-mail  to  MICROSOFT_SECURITY-SIGNOFF-REQUEST@ANNOUNCE.MICROSOFT.COM
The subject line and message body are not used in processing the request,
and can be anything you like.

To verify the digital signature on this bulletin, please download our PGP
key at http://www.microsoft.com/technet/security/notify.asp.

For  more  information on  the  Microsoft  Security Notification  Service
please  visit  http://www.microsoft.com/technet/security/notify.asp.  For
security-related information  about Microsoft products, please  visit the
Microsoft Security Advisor web site at http://www.microsoft.com/security.