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             AUSCERT External Security Bulletin Redistribution

           ESB-2002.241 -- Microsoft Security Bulletin MS02-024
            Authentication Flaw in Windows Debugger can Lead to
                       Elevated Privileges (Q320206)
                                23 May 2002

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

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

Product:                Windows NT
                        Windows 2000
Vendor:                 Microsoft
Impact:                 Administrator Compromise
Access Required:        Existing Account

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Title:      Authentication Flaw in Windows Debugger can Lead to
            Elevated Privileges (Q320206)
Date:       22 May 2002
Software:   Microsoft Windows
Impact:     Elevation of Privilege
Max Risk:   Critical
Bulletin:   MS02-024

Microsoft encourages customers to review the Security Bulletin at: 
http://www.microsoft.com/technet/security/bulletin/MS02-024.asp.
- - ----------------------------------------------------------------------

Issue:
======


The Windows debugging facility provides a means for programs to  
perform diagnostic and analytic functions on applications as they
are running on the operating system. One of these capabilities
allows for a program, usually a debugger, to connect to any running
program, and to take control of it. The program can then issue
commands to the controlled program, including the ability to
start other programs. These commands would then execute in the
same security context as the controlled program. 

There is a flaw in the authentication mechanism for the debugging
facility such that an unauthorized program can gain access to the
debugger. A vulnerability results because an attacker can use
this to cause a running program to run a program of her choice.
Because many programs run as the operating system, this means
that an attacker can exploit this vulnerability to run code as
the operating system itself. She could take any action on the
system including deleting data, adding accounts with
administrative access, or reconfiguring the system. 

A successful attack requires the ability to logon interactively
to the system, either at the console or through a terminal
session. Also, an a successful attack requires the
introduction of code to exploit this vulnerability.
Because best practices recommends restricting the
ability to logon interactively on servers, this
issue most directly affects client systems and terminal servers.

Mitigating Factors:
====================
 - A successful attack requires the ability to logon interactively
   to the target machine, either directly at the console or
   through a terminal session. Best practices strongly militate
   against ever allowing an unprivileged user to interactively
   log onto business-critical systems such as ERP servers,
   database servers, domain controllers and the like.
   If these recommendations have been followed, the
   vulnerability would principally pose a threat only to
   systems like workstations and terminal servers. 

 - A successful attack requires that the attacker be able to
   load code of her choice on the system. Restrictions on a
   user's ability to load and execute arbitrary code could
   potentially prevent a successful attack.

Risk Rating:
============
 - Internet systems: Low
 - Intranet systems: Moderate
 - Client systems: Critical

Patch Availability:
===================
 - A patch is available to fix this vulnerability. Please read the 
   Security Bulletin at
   http://www.microsoft.com/technet/security/bulletin/ms02-024.asp
   for information on obtaining this patch.

- - ---------------------------------------------------------------------

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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