K-044: Microsoft: Vulnerabilities in Internet Explorer

PROBLEM:       Microsoft has released a bulletin addressing three unrelated
               vulnerabilities in Internet Explorer. (1.) The "Frame Domain
               Verification" vulnerablity may allow a malicious web site
               operator to read files from a visiting user's computer. (2.) The
               "Unauthorized Cookie Access" vulnerability may allow a
               malicious web site operator to change or add cookies to a
               visiting user's computer. (3.) The "Malformed Component Attribute"
               vulnerability is a buffer overrun which may allow a malicious
               web site operator to run code of their choice on a visiting users
               computer.
PLATFORM:      Microsoft Internet Explorer 4.0, 4.01, 5.0, and 5.01.
DAMAGE:        (1.) The "Frame Domain Verification" vulnerability could allow a
               malicious web site operator to read .txt, .htm or .js files on
               a visiting user's computer. (2.) The "Unauthorized Cookie Access"
               vulnerability could entice a visiting user to click on a link
               that would allow the malicious web site operator to obtain
               personal information from the cookies stored on the user's
               computer. (3.) The "Malformed Component Attribute" vulnerability
               could allow a malicious web site operator to run code on a
               visiting user's computer which could add, change or delete data
               or reformat the user's hard disk.
SOLUTION:      Load the patch and use the Internet Explorer Security Zone
               (Tools/Internet Options/Security) to increase the web browsers
               security.
VULNERABILITY  With the first two vulnerabilities, "Frame Domain Verification"
ASSESSMENT:    and "Unauthorized Cookie Access" a user would need to visit a
               malicious web site. Most users visit a small number of
               professionally-operated sites which would make the risk LOW. As
               a user browsed more unfamiliar sites the risk would increase.
               The "Malformed Component Attribute" could be sent through
               e-mail, thus making the risk MEDIUM for this vulnerability.

[******  Start Microsoft Bulletin ******]
-----BEGIN PGP SIGNED MESSAGE-----

Microsoft Security Bulletin (MS00-033)
- --------------------------------------

Patch Available for "Frame Domain Verification", "Unauthorized Cookie
Access", and "Malformed Component Attribute"  Vulnerabilities

Originally Posted May 17, 2000

Summary
=======
Microsoft has released a comprehensive patch that eliminates three
security vulnerabilities in Microsoft(r) Internet Explorer  4 and 5
 - The "Frame Domain Verification" vulnerability, which could
   allow a malicious web site operator to read, but not change
   or add, files on the computer of a visiting user.
 - The "Unauthorized Cookie Access" vulnerability, which could
   allow a malicious web site operator to access "cookies"
   belonging to a visiting user.
 - The "Malformed Component Attribute" vulnerability, which
   could allow a malicious web site operator to run code of
   his choice on the computer of a visiting user.

Issue
=====
The three security vulnerabilities eliminated by this patch are
unrelated to each other except by the fact that they all  occur in the
same .dll. We have packaged them together for customer convenience.
The vulnerabilities are
 - "Frame Domain Verification" vulnerability. When a web server
   opens a frame within a window, the IE security model should
   only allow the parent window to access the data in the frame
   if they are in the same domain. However, two functions available
   in IE do not properly perform domain checking, with the result
   that the parent window could open a frame that contains a file
   on the local computer, then read it. This could allow a
   malicious web site operator to view files on the computer of
   a visiting user. The web site operator would need to know (or
   guess) the name and location of the file, and could only view
   file types that can be opened in a browser window.
 - "Unauthorized Cookie Access" vulnerability. By design, the IE
   security model restricts cookies so that they can be read only
   by sites within the originator's domain. However, by using a
   specially-malformed URL, it is possible for a malicious web
   site operator to gain access to another site's cookie and read,
   add or change them. A malicious web site operator would need
   to entice a visiting user into clicking a link in order to
   access each cookie, and could not obtain a listing of the
   cookies available on the visitor's system. Even after
   recovering a cookie, the type and amount of personal information
   would depend on the privacy practices followed by the site that
   placed it there.
 - "Malformed Component Attribute" vulnerability. The code used to
   invoke ActiveX components in IE has an unchecked buffer and
   could be exploited by a malicious web site operator to run code
   on the computer of a visiting user. The unchecked buffer is only
   exposed when certain attributes are specified in conjunction with
   each other.

The patch also eliminates a new variant of the previously-addressed
WPAD Spoofing vulnerability

(http://www.microsoft.com/technet/security/bulletin/ms99-054.asp).

Affected Software Versions
==========================
 - Microsoft Internet Explorer 4.0
 - Microsoft Internet Explorer 4.01
 - Microsoft Internet Explorer 5.0
 - Microsoft Internet Explorer 5.01

Patch Availability
==================
 - http://www.microsoft.com/windows/ie/download/critical/patch6.htm

Note The patches require IE 4.01 Service Pack 2 or IE 5.01 to
install. Customers using versions prior to these may receive a
message reading "This update does not need to be installed on this
system". This message is incorrect. More information is  available in
KB article Q262509.

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 MS00-033,
   http://www.microsoft.com/technet/security/bulletin/fq00-033.asp
 - Microsoft Knowledge Base article Q262509 discusses the overall
   patch and will be available soon.
 - Microsoft Knowledge Base articles Q251108 and 255676 discuss
   the "Frame Domain Verification" vulnerability and will be
   available soon.
 - Microsoft Knowledge Base article Q258430 discusses the
   "Unauthorized Cookie Access" vulnerability and will be available
   soon.
 - Microsoft Knowledge Base article Q261257 discusses the
   "Malformed Component Attribute" vulnerability and will be
   available soon.
 - Microsoft Knowledge Base (KB) article Q247333,
   Web Proxy Auto-Discovery "Spoofing" May Change Proxy Settings,
   http://www.microsoft.com/technet/support/kb.asp?ID=247333
 - 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 the following people for working with us to protect
customers
 - Mead & Company's Andrew Nosenko for reporting the
  "Frame Domain Verification" issue to us
 - Marc Slemko for reporting the "Unauthorized Cookie Access"
   vulnerability to us.
 - UNYUN, the Shadow Penguin Security Research Group of Japan,
   for reporting the "Malformed Component Attribute" vulnerability
   to us.

Revisions
=========
 - May 17, 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 May 17, 2000

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

-----BEGIN PGP SIGNATURE-----
Version PGP 6.0.2

iQEVAwUBOSM9No0ZSRQxA/UrAQGTCggAni1/ZkBUGBT1XnI0anqPhY7+cTu0Q1is
GjITriIFM8e0gDC9RxYE4Gjh7/AlvSfUZQz3ApxFzi2ltavJULn7vE7bEFNGhj1a
uUvEApqJ/xeLreMMNMQx1sz6HN15U4HJjO9Q9If98fdr0UELkFFciVeJXGSDEYCT
f/UcZWKxZIQlxG2QgGAqfMSOrYu/FyYfuTOawIPbwQ3s2kKJ8kH477jS+kpkxzoC
I29HpQpW/BMDW3HtkX+HWx2Q592X958j7dkxWsGkCgVbbVCjozOLFRLk57awkHrU
mvLezVxT4y1l2NV0xIgEXaoiMPzHGO+Voo7xUdQloSIF+ztMWv9Zkw==
=EwPj
-----END PGP SIGNATURE-----

[******  End Microsoft Bulletin ******]

    Voice:          +1 925-422-8193 (7 x 24)
    FAX:            +1 925-423-8002
    STU-III:        +1 925-423-2604
    E-mail:          ciac@llnl.gov
    World Wide Web:  http://www.ciac.org/
                     http://ciac.llnl.gov
                     (same machine -- either one will work)
    Anonymous FTP:   ftp.ciac.org
                     ciac.llnl.gov
                     (same machine -- either one will work)