Microsoft Security Bulletin (MS00-026)

Patch Available for "Mixed Object Access" Vulnerability

Originally Posted: April 20, 2000

Summary

---

Microsoft has released a patch that eliminates a security
vulnerability in Microsoft(r) Windows(r) 2000 that could, under very
specific conditions, allow a malicious user to change information in
the Active Directory that he should not be able to change.

Frequently asked questions regarding this vulnerability and
the patch can be found at
http://www.microsoft.com/technet/security/bulletin/fq00-026.asp

Issue

Active Directory allows for access control of directory objects on a
per-attribute basis. However, the vulnerability at issue here could
allow a malicious user to modify object attributes that he does not
have permission to modify, as long as he combined the operation in a
particular way with ones involving attributes that he does have
permission to modify.

The vulnerability does not afford the malicious user an opportunity to
modify all objects in a class - only the specific class objects for
which he has permission to modify at least one attribute. Further, the
vulnerability provides no capability to bypass normal authentication
or Windows 2000 auditing, so administrators could determine if this
vulnerability were being exploited, and by whom.

Affected Software Versions

• Windows 2000 Server
• Windows 2000 Advanced Server

Note The vulnerability only affects the above products when they are
used as domain controllers.

Patch Availability

• http://www.microsoft.com/Downloads/Release.asp?ReleaseID=20490

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 MS00-026,
  http://www.microsoft.com/technet/security/bulletin/fq00-026.asp
• Microsoft Knowledge Base article Q259401 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 Technical Support is available at
http://support.microsoft.com/support/contact/default.asp.

Acknowledgments

Microsoft thanks Sebastien Malbois (mailto:[email protected]) of
Bouygues Construction (http://www.bouygues-construction.com/) for
reporting this issue to us and working with us to protect customers.

Revisions

• April 20, 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 April 20, 2000

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