Microsoft Security Bulletin (MS99-041)

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Microsoft Security Bulletin (MS99-041)
--------------------------------------

Tool Available for "RASMAN Security Descriptor" Vulnerability
Originally Posted: September 30, 1999

Summary
=======
Microsoft has released a patch that eliminates a vulnerability in
Microsoft(r) Windows NT(r) 4.0.  The vulnerability could enable a user to
execute arbitrary code on a Windows NT machine under  certain conditions.

Frequently asked questions regarding this vulnerability can be found
at http://www.microsoft.com/security/bulletins/MS99-041faq.asp.

Issue
=====
The security descriptor that secures the Remote Access Connection Manager,
RASMAN.EXE, contains  an inappropriate ACE in its DACL and would allow an
unprivileged user to levy requests on it via  the Service Control Manager.
Among the actions that could be requested is to change the location  and
name of the executable code for the service. By doing so, a malicious user
could substitute  arbitrary code for the legitimate service, which then
would run in a System Context.

A malicious user could only exploit this vulnerability if he or she had a
valid userid and  password on the target machine. If the machine allowed
users to log on from the network, the  vulnerability could be remotely
exploited. In addition, the arbitrary code could, under certain  conditions,
reside on a remote machine. A tool is available to reset the permissions to
the  appropriate value and eliminate the vulnerability, and should be run
against any machine that  allows unprivileged users to perform either
interactive or network logons under any account.

Affected Software Versions
==========================
 - Microsoft Windows NT 4.0 Workstation
 - Microsoft Windows NT 4.0 Server
 - Microsoft Windows NT 4.0 Server, Enterprise Edition
 - Microsoft Windows NT 4.0 Server, Terminal Server Edition

Tool Availability
=================
 - ftp://ftp.microsoft.com/bussys/winnt/winnt-public/fixes/
   usa/nt40/Hotfixes-PostSP6/Security/Rasman-fix/

NOTE: Line breaks have been inserted into the above URL for readability.

More Information
================
Please see the following references for more information related to this
issue.
 - Microsoft Security Bulletin MS99-041: Frequently Asked Questions,
   http://www.microsoft.com/security/bulletins/MS99-041faq.asp.
 - Microsoft Knowledge Base (KB) article Q242294,
   Security Descriptor Allows Privilege Elevation on Remote Computers,
   http://support.microsoft.com/support/kb/articles/q242/2/94.asp.
   (Note: It may take 24 hours from the original posting of this
   bulletin for this KB article to be visible.)
 - Microsoft Security Advisor web site,
   http://www.microsoft.com/security/default.asp.

Obtaining Support on this Issue
===============================
This is a fully supported patch. Information on contacting Microsoft
Technical Support is available at
http://support.microsoft.com/support/contact/default.asp.

Acknowledgments
===============
Microsoft acknowledges Alberto Rodríguez Aragonés for bringing this issue to
our attention.

Revisions
=========
 - September 30, 1999: Bulletin Created.

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