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

           ESB-2001.391 -- Microsoft Security Bulletin MS01-048
  Malformed Request to RPC Endpoint Mapper can Cause RPC Service to Fail
                             11 September 2001

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

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

Product:                Windows NT 4.0
Vendor:                 Microsoft
Impact:                 Denial of Service
Access Required:        Remote

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- - ----------------------------------------------------------------------
Title:      Malformed Request to RPC Endpoint Mapper can Cause RPC
            Service to Fail
Date:       10 September 2001
Software:   Microsoft(r) Windows NT(r) 4.0
Impact:     Denial of service
Bulletin:   MS01-048

Microsoft encourages customers to review the Security Bulletin at:
http://www.microsoft.com/technet/security/bulletin/MS01-048.asp.
- - ----------------------------------------------------------------------

Issue:
======
The RPC endpoint mapper allows RPC clients to determine the port
number currently assigned to a particular RPC service. The Windows NT
4.0 endpoint mapper contains a flaw that causes it to fail upon
receipt of a request that contains a particular type of malformed
data. 

Because the endpoint mapper runs within the RPC service itself,
exploiting this vulnerability would cause the RPC service itself to
fail, with the attendant loss of any RPC-based services the server
offers, as well as potential loss of some COM functions. Normal
service could be restored by rebooting the server. 

Mitigating Factors:
====================
 - Standard security recommendations call for port 135 - the port
   on which the RPC endmapper operates - to be blocked at the
   firewall. If this were done, Internet-based attackers would not
   be able to exploit this vulnerability. 

Patch Availability:
===================
 - A patch is available to fix this vulnerability. Please read the 
   Security Bulletin at
   http://www.microsoft.com/technet/security/bulletin/ms01-048.asp
   for information on obtaining this patch.

Acknowledgment:
===============
 - Seiichi Tatsukawa of Rational Software (http://www.rational.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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