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ESB-2003.0049 -- Microsoft Security Bulletin MS03-003 -- Flaw in how Outlook 2002 handles V1 Exchange Server Security Certificates could lead to Information Disclosure (812262)

Date: 24 January 2003

Click here for printable version
Click here for PGP verifiable version
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===========================================================================
             AUSCERT External Security Bulletin Redistribution

           ESB-2003.0049 -- Microsoft Security Bulletin MS03-003
 Flaw in how Outlook 2002 handles V1 Exchange Server Security Certificates
               could lead to Information Disclosure (812262)
                              24 January 2003

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

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

Product:                Outlook 2002
Vendor:                 Microsoft
Operating System:       Windows
Impact:                 Access Confidential Data

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

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- - ----------------------------------------------------------------------
Title:      Flaw in how Outlook 2002 handles V1 Exchange Server 
            Security Certificates could lead to Information 
            Disclosure (812262)
Date:       22 January 2002
Software:   Microsoft Outlook 2002
Impact:     Information Disclosure
Max Risk:   Moderate
Bulletin:   MS03-003

Microsoft encourages customers to review the Security Bulletins at: 
http://www.microsoft.com/technet/security/bulletin/MS03-003.asp
http://www.microsoft.com/security/security_bulletins/MS03-003.asp
- - ----------------------------------------------------------------------

Issue:
======
Microsoft Outlook 2002 provides the facility to encrypt e-mails 
sent between e-mail recipients. Encryption is used to prevent 
parties other than the intended recipients from reading the 
contents of an e-mail. Outlook uses public key certificates to 
facilitate the exchange of the cryptographic keys that are used in 
the encryption process, and Outlook offers a number of different 
options as to what type of certificates can be used. S/MIME 
certificates are the most commonly used (and are not affected by 
the vulnerability that is the subject of this bulletin), but there 
are other certificate options including V1 Exchange Server Security 
certificates. 

A vulnerability exists because there is a flaw in the way Outlook 
2002 handles a V1 Exchange Server Security certificate when using 
it to encrypt e-mail. As a result of this flaw, Outlook fails to 
encrypt the mail correctly and the message will be sent in plain 
text. This could cause the information in the e-mail to be exposed 
when the user believed it to be protected through encryption.

Mitigating Factors:
====================
- - -This vulnerability only affects encryption when a V1 Exchange 
 Server Security certificate is used. S/MIME encryption, which is 
 the most widely used form of e-mail encryption used by Outlook, is 
 not affected. 

- - -This vulnerability only affects Outlook 2002 and only when sending 
 HTML e-mail.

Risk Rating:
============
 Moderate

Patch Availability:
===================
 - A patch is available to fix this vulnerability. Please read the 
   Security Bulletins at
   http://www.microsoft.com/technet/security/bulletin/ms03-003.asp
   http://www.microsoft.com/security/security_bulletins/ms03-003.asp

   for information on obtaining this patch.

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

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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AusCERT did not write the document quoted above, AusCERT has had no control
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Previous advisories and external security bulletins can be retrieved from:

        http://www.auscert.org.au/render.html?cid=1980

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 member emergencies only.

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