US-CERT Technical Cyber Security Alert TA06-270A -- Microsoft Internet Explorer WebViewFolderIcon ActiveX Vulnerability

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                 National Cyber Alert System

           Technical Cyber Security Alert TA06-270A

Microsoft Internet Explorer WebViewFolderIcon ActiveX Vulnerability

Original release date: September 27, 2006
Last revised: –
Source: US-CERT

Systems Affected

 * Microsoft Windows
 * Microsoft Internet Explorer

Overview

The Microsoft Windows WebViewFolderIcon ActiveX control contains an
integer overflow vulnerability that could allow a remote attacker
to execute arbitrary code.

I. Description

The Microsoft Windows WebViewFolderIcon ActiveX control contains an
integer overflow vulnerability. An attacker could exploit this
vulnerability through Microsoft Internet Explorer (IE) or any other
application that hosts the WebViewFolderIcon control. More
information is available in Vulnerability Note VU#753044.

Exploit code for this vulnerability is publicly available.

II. Impact

By convincing a user to open a specially crafted HTML document,
such as a web page or HTML email message, a remote attacker could
execute arbitrary code with the privileges of the user who is
running the program that hosts the WebViewFolderIcon control.

III. Solution

Microsoft has not released an update for this
vulnerability. Consider the following workarounds and best
practices:

Disable the WebViewFolderIcon ActiveX control

 To protect against this specific vulnerability, disable the
 WebViewFolderIcon control by setting the kill bit for the
 following CLSID:

   {844F4806-E8A8-11d2-9652-00C04FC30871}

 More information about how to set the kill bit is available in
 Microsoft Support Document 240797.

Disable ActiveX

 To protect against this and other ActiveX and COM
 vulnerabilities, disable ActiveX in the Internet Zone and any
 other zone that might be used by an attacker. Instructions for
 disabling ActiveX in the Internet Zone can be found in the
 "Securing Your Web Browser" document and the Malicious Web
 Scripts FAQ.

Render email as plain text

 To protect against this and other vulnerabilities that require a
 victim to load a malicious HTML document, configure email clients
 to render email as plain text.

Do not follow unsolicited links

 To protect against this and other vulnerabilities that require a
 victim to load a malicious HTML document, do not follow
 unsolicited or untrusted links.

 In order to convince users to visit their sites, attackers often
 use URL encoding, IP address variations, long URLs, intentional
 misspellings, and other techniques to create misleading links. Do
 not click on unsolicited links received in email, instant
 messages (IMs), web forums, or internet relay chat (IRC)
 channels. Type URLs directly into the browser to avoid these
 misleading links. While these are generally good security
 practices, following these behaviors will not prevent
 exploitation of this vulnerability in all cases, particularly if
 a trusted site has been compromised or allows cross-site
 scripting.

IV. References

 * Vulnerability Note VU#753044 -
   <http://www.kb.cert.org/vuls/id/753044>

 * Securing Your Web Browser -
   <http://www.us-cert.gov/reading_room/securing_browser/>

 * Malicious Web Scripts FAQ -
   <http://www.cert.org/tech_tips/malicious_code_FAQ.html>

 * CVE-2006-3730 -
   <http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-3730>

 * Microsoft Support Document 240797 -
   <http://support.microsoft.com/kb/240797>

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The most recent version of this document can be found at:

 <http://www.us-cert.gov/cas/techalerts/TA06-270A.html>

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Feedback can be directed to US-CERT Technical Staff. Please send
email to <[email protected]> with "TA06-270A Feedback VU#753044" in the
subject.

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Produced 2006 by US-CERT, a government organization.

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Revision History

September 27, 2006: Initial release

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