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CA-2001-36 Microsoft Internet Explorer Does Not Respect
Content-Disposition and Content-Type MIME Headers
release date: December 19, 2001
Last revised: --
revision history can be found at the end of this file.
Internet Explorer 6.0 for Windows
* Microsoft Outlook, Outlook Express, or any other software that
utilizes vulnerable versions of Internet Explorer to render HTML
Internet Explorer contains a vulnerability in its handling of
certain MIME headers in web pages and HTML email messages. This
vulnerability may allow an attacker to execute arbitrary code on the
victim's system when the victim visits a web page or views an HTML
and HTML email messages usually contain HTML text, but other
files may also be included. The MIME headers Content-Disposition and
Content-Type provide the information needed by the HTML rendering
software to determine the type of these files. In Microsoft Internet
Explorer, these MIME headers are consulted when evaluating whether to
process an embedded file, but they are ignored when the file is
if an executable (.exe) file is embedded with MIME headers
that misrepresent it as a JPEG image file (.jpg), Internet Explorer
will treat the file as a JPEG when evaluating whether it is safe to
open. Once this evaluation is complete, the file will be opened
according to its .exe file extension and will be executed on the local
results in a vulnerability that allows attackers to
bypass the security measures that typically screen out executable code.
This code would be executed with the privileges the user who views the
web page or email message.
who view a malicious web site or HTML email message may be able
to prevent the execution of the attacker's code by using the download
progress dialog box to cancel the download. However, depending on the
size of the embedded file and the speed of the network connection,
users may not have time to cancel the file download.
is tracking this vulnerability as VU#443699, which
corresponds directly to the "File Execution" vulnerability
Microsoft Security Bulletin MS01-058. This Microsoft bulletin is
is being referenced in CVE as CAN-2001-0727.
a user to view a malicious web page or HTML email
message, a remote attacker can cause the user to execute arbitrary
code. Any such code would run with the privileges of the user who
attempted to view the content.
a patch from your vendor
Microsoft has released a cumulative patch for Internet Explorer that
corrects this vulnerability and several others. For more information
about the patch and the vulnerabilities, please see Microsoft
Security Bulletin MS01-058:
Disable file downloads in all security zones
As a workaround, you can prevent malicious files from being
downloaded by disabling file downloads in all security zones. Note
that this decision will impact browser functionality.
A. - Vendor Information
contains information provided by vendors for this
advisory. As vendors report new information to the CERT/CC, we will
update this section and note the changes in our revision history. If
particular vendor is not listed below, we have not received their
documents regarding this vulnerability are available
Coordination Center acknowledges Jouko Pynnonen as the
discoverer of this vulnerability and thanks Microsoft for the
information presented in MS01-058.
This document was written by Jeffrey P. Lanza.
is available from:
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Fax: +1 412-268-6989
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2001 Carnegie Mellon University.
19, 2001: Initial release
Version: PGP 6.5.8
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