-=PCTechTalk=- (Fwd) Microsoft Security Bulletin MS02-064: Windows 2000 Defau


------- Forwarded message follows -------
Subject:                Microsoft Security Bulletin MS02-064: Windows 2000 
Default Permissions Could Allow Trojan Horse Program (Q327522)
Date sent:              Wed, 30 Oct 2002 21:51:27 -0800

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

Title:      Windows 2000 Default Permissions Could Allow Trojan Horse
            Program (Q327522)
Date:       30 October 2002
Software:   Windows 2000
Impact:     Trojan Horse program execution 
Max Risk:   Moderate
Bulletin:   MS02-064

Microsoft encourages customers to review the Security Bulletin at:
http://www.microsoft.com/technet/security/bulletin/MS02-064.asp. -
----------------------------------------------------------------------

Issue:
======
On Windows 2000, the default permissions provide the Everyone group 
with
Full access (Everyone:F) on the system root folder (typically, C:\). In
most cases, the system root is not in the search path. However, under
certain conditions - for instance, during logon or when applications 
are
invoked directly from the Windows desktop via Start | Run - it can be. 

This situation gives rise to a scenario that could enable an attacker 
to
mount a Trojan horse attack against other users of the same system, by
creating a program in the system root with the same name as some
commonly used program, then waiting for another user to subsequently 
log
onto the system and invoke the program. The Trojan horse program would
execute with the user's own privileges, thereby enabling it to take any
action that the user could take. 

The simplest attack scenario would be one in which the attacker knew
that a particular system program was invoked by a logon script. In that
case, the attacker could create a Trojan horse with the same name as 
the
system program, which would then be executed by the logon script the
next time someone logged onto the system. Other scenarios almost
certainly would require significantly greater user interaction - for
instance, convincing a user to start a particular program via Start |
Run - and would necessitate the use of social engineering. 

The systems primarily at risk from this vulnerability would be
workstations that are shared between multiple users, and local
terminal server sessions. Other systems would be at significantly
less risk: 

 - Workstations that are not shared between users would be at no
   risk, because the attacker would require the ability to log onto the
   system in order to place the Trojan horse. 

 - Servers would be at no risk, if standard best practices have
   been followed that advocate only allowing trusted users to log
   onto them. 

 - Remote Terminal server sessions would be at little risk,
   because each user's environment is isolated. That is, the system 
root
   is never the current folder - instead, the user's Documents and
   Settings folder is, but the permissions on this folder would not
   enable an attacker to place a Trojan horse there. 

Mitigating Factors:
====================
 - An attacker would require the ability to log onto the system
   interactively in order to place the Trojan horse program. It
   could not be placed remotely 

 - As discussed above, dedicated workstations, servers and remote
   terminal server sessions would be at less risk (or, in some cases,
   none at all) from the vulnerability. 

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

Patch Availability:
===================
 - This vulnerability requires an administrative procedure rather
   than a patch. The needed changes are discussed in the FAQ.  
   Please read the Security Bulletin at
   http://www.microsoft.com/technet/security/bulletin/ms02-064.asp
   for information on obtaining this patch.

Acknowledgment:
===============
 - Jason Miller of Security Focus (http://www.securityfocus.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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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...a cat is a diagram and a pattern of subtle air...

Grant Karpik
gkarpik@xxxxxxxxx


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