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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

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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.

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