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securityvulnsSecurityvulnsSECURITYVULNS:DOC:1444
HistoryMar 30, 2001 - 12:00 a.m.

Security Bulletin MS01-020

2001-03-3000:00:00
vulners.com
50

Title: Incorrect MIME Header Can Cause IE to Execute E-mail
Attachment
Date: 29 March 2001
Software: Microsoft Internet Explorer
Impact: Run code of attacker's choice.
Bulletin: MS01-020

Microsoft encourages customers to review the Security Bulletin
at: http://www.microsoft.com/technet/security/bulletin/MS01-020.asp.


Issue:

Because HTML e-mails are simply web pages, IE can render them and
open
binary attachments in a way that is appropriate to their MIME types.
However, a flaw exists in the type of processing that is specified
for
certain unusual MIME types. If an attacker created an HTML e-mail
containing an executable attachment, then modified the MIME header
information to specify that the attachment was one of the unusual
MIME
types that IE handles incorrectly, IE would launch the attachment
automatically when it rendered the e-mail.

An attacker could use this vulnerability in either of two scenarios.
She could host an affected HTML e-mail on a web site and try to
persuade another user to visit it, at which point script on a web
page
could open the mail and initiate the executable. Alternatively, she
could send the HTML mail directly to the user. In either case, the
executable attachment, if it ran, would be limited only by user's
permissions on the system.

Mitigating Factors:

The vulnerability could not be exploited if File Downloads have been
disabled in the Security Zone in which the e-mail is rendered. This
is
not a default setting in any zone, however.

Patch Availability:

Acknowledgment:


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.