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                             CERT-Renater

                  Note d'Information No. 2012/VULN368
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DATE                : 18/09/2012

HARDWARE PLATFORM(S): /


OPERATING SYSTEM(S) : Systems running Internet Explorer versions 6, 7,
                                  8, 9.

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http://technet.microsoft.com/en-us/security/advisory/2757760
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Microsoft Security Advisory (2757760)
Vulnerability in Internet Explorer Could Allow Remote Code Execution

Published: Monday, September 17, 2012

Version: 1.0
General Information
Executive Summary

Microsoft is investigating public reports of a vulnerability in
Internet Explorer 6, Internet Explorer 7, Internet Explorer 8, and
Internet Explorer 9. Internet Explorer 10 is not affected. Microsoft is
aware of targeted attacks that attempt to exploit this vulnerability.

A remote code execution vulnerability exists in the way that Internet
Explorer accesses an object that has been deleted or has not been
properly allocated. The vulnerability may corrupt memory in a way that
could allow an attacker to execute arbitrary code in the context of the
current user within Internet Explorer. An attacker could host a
specially crafted website that is designed to exploit this
vulnerability through Internet Explorer and then convince a user to
view the website.

On completion of this investigation, Microsoft will take the
appropriate action to protect our customers, which may include
providing a solution through our monthly security update release
process, or an out-of-cycle security update, depending on customer
needs.

We are actively working with partners in our Microsoft Active
Protections Program (MAPP) to provide information that they can use to
provide broader protections to customers. In addition, we are actively
working with partners to monitor the threat landscape and take action
against malicious sites that attempt to exploit this vulnerability.

Microsoft continues to encourage customers to follow the guidance in
the Microsoft Safety & Security Center of enabling a firewall, applying
all software updates and installing anti-virus and anti-spyware
software.


Mitigating Factors:

    By default, Internet Explorer on Windows Server 2003, Windows
Server 2008, and Windows Server 2008 R2 runs in a restricted mode that
is known as Enhanced Security Configuration. This mode mitigates this
vulnerability.

    By default, all supported versions of Microsoft Outlook, Microsoft
Outlook Express, and Windows Mail open HTML email messages in the
Restricted sites zone. The Restricted sites zone, which disables script
and ActiveX controls, helps reduce the risk of an attacker being able
to use this vulnerability to execute malicious code. If a user clicks a
link in an email message, the user could still be vulnerable to
exploitation of this vulnerability through the web-based attack
scenario.

    An attacker who successfully exploited this vulnerability could
gain the same user rights as the current user. Users whose accounts are
configured to have fewer user rights on the system could be less
impacted than users who operate with administrative user rights.

    In a web-based attack scenario, an attacker could host a website
that contains a webpage that is used to exploit this vulnerability. In
addition, compromised websites and websites that accept or host
user-provided content or advertisements could contain specially crafted
content that could exploit this vulnerability. In all cases, however,
an attacker would have no way to force users to visit these websites.

Instead, an attacker would have to convince users to visit the website,
typically by getting them to click a link in an email message or
Instant Messenger message that takes users to the attacker's website.

Recommendation. See the Suggested Actions section of this advisory for
more information.

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