Operating System:

Published:

10 August 2000

Protect yourself against future threats.

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

===========================================================================
              AUSCERT External Security Bulletin Redistribution
                             
           ESB-2000.207 -- Microsoft Security Bulletin (MS00-057)
    Patch Available for "File Permission Canonicalization" Vulnerability
                               11 August 2000

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

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

Product:		Internet Information Server 4.0
                        Internet Information Server 5.0
Vendor:			Microsoft
Operating System:       MS Windows Server Platforms
Platform:               N/A

Impact:			Increased Privileges
Access Required:	Remote

- --------------------------BEGIN INCLUDED TEXT--------------------

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

Microsoft Security Bulletin (MS00-057)
- - --------------------------------------

Patch Available for "File Permission Canonicalization" Vulnerability

Originally posted: August 10, 2000

Summary
=======
Microsoft has released a patch that eliminates a security
vulnerability in Microsoft(r) Internet Information Server. Under very
restricted conditions, the vulnerability could allow a malicious user
to gain additional permissions to certain types of files hosted on a
web server.

Frequently asked questions regarding this vulnerability and the patch
can be found at
http://www.microsoft.com/technet/security/bulletin/fq00-057.asp

Issue
=====
A canonicalization error can, under certain conditions, cause IIS 4.0
or 5.0 to apply incorrect permissions to certain types of files. If
an affected file residing in a folder with restrictive permissions
were requested via a particular type of malformed URL, the
permissions actually used would be those of a folder in the file's
parentage chain, but not those of the folder the file actually
resides in. If the ancestor folder's permissions were more permissive
than those of the correct folder, the malicious user would gain
additional privileges to the affected file.

The vulnerability is subject to several significant restrictions:
 - It only affects CGI scripts and file types that are implemented
   via ISAPI extensions. It does not affect static web page or
   non-web file types such as .exe, .doc or .bat
 - It only affects servers that expose a web folder structure that
   mirrors the physical folder structure on the server.
 - It does not allow arbitrary permissions to be selected, only
   permissions present on an ancestor folder
 - It provides no way to enumerate the server and locate files that
   could be affected by the vulnerability.

Affected Software Versions
==========================
 - Microsoft Internet Information Server 4.0
 - Microsoft Internet Information Server 5.0

Patch Availability
==================
 - Microsoft Internet Information Server 4.0:
   http://www.microsoft.com/Downloads/Release.asp?ReleaseID=23667
 - Microsoft Internet Information Server 5.0:
   http://www.microsoft.com/Downloads/Release.asp?ReleaseID=23665

Note: Additional security patches are available at the Microsoft
Download Center

More Information
================
Please see the following references for more information related to
this issue.
 - Frequently Asked Questions: Microsoft Security Bulletin MS00-057,
   http://www.microsoft.com/technet/security/bulletin/fq00-057.asp
 - Microsoft Knowledge Base article Q269862 discusses this issue and
   will be available soon.
 - Microsoft TechNet Security web site,
   http://www.microsoft.com/technet/security/default.asp

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

Acknowledgments
===============
Microsoft thanks  Burt Abreu & Søren Skov of VBExplorer.com for
reporting this issue to us and working with us to protect customers.

Revisions
=========
August 10, 2000: Bulletin Created.

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

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.

Last Updated August 10, 2000

(c) 2000 Microsoft Corporation. All rights reserved. Terms of use.



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

iQEVAwUBOZLvrY0ZSRQxA/UrAQHewgf+Ks8c/EmNUdguRAru3xmrwYJfL5Pxkmlv
RytMqC1iqTVUdUtrOoZaThB4m6WfaYDTLoiV9jJrnVHJ4t0/geoIEzUkQIw3rvY2
kVZAWS+vSG3gCOHKN/0710Go1lKCKTHhLh4vVVc9LrvXRTAYE88Med2EAKrMsRNd
LG3WrWArdFTdSfwqDQ5jJ48xf+qYHK63O+Yh4MdLXjpY2Bxd6U/eHz7eIn2qhpEx
BoqGpLcHN1KKmGbcTIgUzYpIXo+I10c1efVIgH9sCPEXGelOVtzFg7dFGOQjF9xo
pn2XjQDnD/tyh7RodSAvyxy5zkwyMwMF+x8nNRDodACMA7F1YeC07A==
=LDZS
- -----END PGP SIGNATURE-----

- --------------------------END INCLUDED TEXT--------------------

This security bulletin is provided as a service to AusCERT's members.  As
AusCERT did not write the document quoted above, AusCERT has had no control
over its content.  The decision to use any or all of this information is
the responsibility of each user or organisation, and should be done so in
accordance with site policies and procedures.

NOTE: This is only the original release of the security bulletin.  It may
not be updated when updates to the original are made.  If downloading at
a later date, it is recommended that the bulletin is retrieved directly
from the original authors to ensure that the information is still current.

Contact information for the authors of the original document is included
in the Security Bulletin above.  If you have any questions or need further
information, please contact them directly.

Previous advisories and external security bulletins can be retrieved from:

	http://www.auscert.org.au/Information/advisories.html

If you believe that your system has been compromised, contact AusCERT or
your representative in FIRST (Forum of Incident Response and Security
Teams).

Internet Email: auscert@auscert.org.au
Facsimile:	(07) 3365 7031
Telephone:	(07) 3365 4417 (International: +61 7 3365 4417)
		AusCERT personnel answer during Queensland business hours
		which are GMT+10:00 (AEST).
		On call after hours for emergencies.


-----BEGIN PGP SIGNATURE-----
Version: 2.6.3i
Charset: noconv
Comment: ftp://ftp.auscert.org.au/pub/auscert/AUSCERT_PGP.key

iQCVAwUBOZgILCh9+71yA2DNAQHCAAQAi5E757xOnb4aGwBMI+TVg3FjSvosK2Ub
c1eJ/DtceLQ0aVVaUJg+SFi6L7Y+Ttwr/imPXTgWJRDsfIuADnQDZ5TKnWq7KGaO
KMQ7eaGaVPsglnWeQa1tZVr7vnSKmMLH19ESM+UXVTDk5lu9we+4aiDnlD+qD8Ff
FcUthMXpKtM=
=dO1N
-----END PGP SIGNATURE-----