Hash: SHA1

             AUSCERT External Security Bulletin Redistribution

                          ESB-2006.0697 -- [Win]
         Microsoft Internet Explorer VML Buffer Overflow (Update)
                             27 September 2006


        AusCERT Security Bulletin Summary

Product:              Internet Explorer
Publisher:            US-CERT
Operating System:     Windows
Impact:               Execute Arbitrary Code/Commands
Access:               Remote/Unauthenticated
CVE Names:            CVE-2006-3866

Ref:                  AU-2006.0034

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Hash: SHA1

                        National Cyber Alert System

                 Technical Cyber Security Alert TA06-262A

Microsoft Internet Explorer VML Buffer Overflow

   Original release date: September 19, 2006
   Last revised: September 26, 2006
   Source: US-CERT

Systems Affected

     * Microsoft Windows
     * Microsoft Internet Explorer


   Microsoft Internet Explorer (IE) fails to properly handle Vector
   Markup Language (VML) tags. This creates a buffer overflow
   vulnerability that could allow a remote attacker to execute arbitrary

I. Description

   Microsoft Internet Explorer contains a stack buffer overflow in code
   that handles VML. More information is available in Vulnerability Note
   VU#416092, Microsoft Security Advisory (925568), and Microsoft
   Security Bulletin MS06-055.

   Note that this vulnerability is being exploited.

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 running IE.

III. Solution

Apply update from Microsoft

   Microsoft has provided an update to correct this vulnerability in
   Microsoft Security Bulletin MS06-055.

   This update is available on the Microsoft Update site.

   System administrators may wish to consider using Windows Server Update
   Services (WSUS).

Disable VML support

   Microsoft Security Advisory (925568) suggests the following techniques
   to disable VML support:

     * Un-register Vgx.dll on Windows XP Service Pack 1; Windows XP
       Service Pack 2; Windows Server 2003 and Windows Server 2003
       Service Pack 1

     * Modify the Access Control List on Vgx.dll to be more restrictive

     * Configure Internet Explorer 6 for Microsoft Windows XP Service
       Pack 2 to disable Binary and Script Behaviors in the Internet and
       Local Intranet security zone

   Disabling VML support may cause web sites and applications that use
   VML to function improperly.

Render email as plain text

   Microsoft Security Advisory (925568) suggests configuring Microsoft
   Outlook and Outlook Express to render email messages in plain text

Do not follow unsolicited 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, 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#416092 -

     * Microsoft Security Bulletin MS06-055-

     * Microsoft Security Advisory (925568) -

     * Securing Your Web Browser-

     * Microsoft Update - <https://update.microsoft.com/microsoftupdate/>

     * CVE-2006-3866 -


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


   Feedback can be directed to US-CERT Technical Staff. Please send
   email to <cert@cert.org> with "TA06-262A Feedback VU#416092" in the

   For instructions on subscribing to or unsubscribing from this
   mailing list, visit <http://www.us-cert.gov/cas/signup.html>.

   Produced 2006 by US-CERT, a government organization.

   Terms of use:


Revision History

   September 19, 2006: Initial release
   September 21, 2006: Fixed misspelling and removed IE-specific
language from Solution section
   September 26, 2006: Added update information and added a reference
to Microsoft Update

Version: GnuPG v1.2.1 (GNU/Linux)


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