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UNIRAS Brief - 418/06 - US-CERT Technical Cyber Security Alert TA06-167A -- Microsoft Excel Vulnerability



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   UNIRAS (UK Govt CERT) Briefing Notice - 418/06 dated 19.06.06  Time: 11:00  
  UNIRAS is part of NISCC (National Infrastructure Security Co-ordination Centre)
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  UNIRAS material is also available from its website at www.uniras.gov.uk and
         Information about NISCC is available from www.niscc.gov.uk
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Title
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US-CERT Technical Cyber Security Alert TA06-167A -- Microsoft Excel Vulnerability 

Detail
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                        National Cyber Alert System

                Technical Cyber Security Alert TA06-167A


Microsoft Excel Vulnerability

   Original release date: June 16, 2006
   Last revised: --
   Source: US-CERT


Systems Affected

     * Microsoft Excel 2003
     * Microsoft Excel XP (2002)
     * Microsoft Excel for Mac

   Microsoft Excel is included with Microsoft Office. Other versions of
   Excel, and other Office programs may be affected or act as attack
   vectors.


Overview

   An unspecified vulnerability in Microsoft Excel could allow an
   attacker to execute arbitrary code on a vulnerable system.


I. Description

   Microsoft Excel contains an unspecified vulnerability. Opening a
   specially crafted Excel document, including documents hosted on web
   sites or attached to email messages, could trigger the vulnerability.

   Office documents can contain embedded objects. For example, a
   malicious Excel document could be embedded in an Word or PowerPoint
   document. Office documents other than Excel documents could be used as
   attack vectors.

   For more information, please see Vulnerability Note VU#802324.


II. Impact

   By convincing a user to open a specially crafted Excel document, an
   attacker could execute arbitrary code on a vulnerable system. If the
   user has administrative privileges, the attacker could gain complete
   control of the system.


III. Solution

   At the time of writing, there is no complete solution available.
   Consider the following workarounds:

Do not open untrusted Excel documents

   Do not open unfamiliar or unexpected Excel or other Office documents,
   including those received as email attachments or hosted on a web site.
   Please see Cyber Security Tip ST04-010 for more information.

Do not rely on file extension filtering

   In most cases, Windows will call Excel to open a document even if the
   document has an unknown file extension. For example, if document.x1s
   (note the digit "1") contains the correct file header information,
   Windows will open document.x1s with Excel.


Appendix A. References

     * Vulnerability Note VU#802324 -
       <http://www.kb.cert.org/vuls/id/802324>

     * Cyber Security Tip ST04-010 -
       <http://www.us-cert.gov/cas/tips/ST04-010.html>


 ____________________________________________________________________

   Information used in this document came from SANS and Microsoft.
 ____________________________________________________________________

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

     <http://www.us-cert.gov/cas/techalerts/TA06-167A.html>
 ____________________________________________________________________

   Feedback can be directed to US-CERT Technical Staff. Please send
   email to <cert@xxxxxxxx> with "TA06-167A Feedback VU#802324" in the
   subject.
 ____________________________________________________________________

   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:

     <http://www.us-cert.gov/legal.html>
 ____________________________________________________________________


Revision History

   June 16, 2006: Initial release





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For additional information or assistance, please contact the HELP Desk by 
telephone or Not Protectively Marked information may be sent via 
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Tel: +44 (0) 870 487 0748 Ext 4511
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Outside of Office Hours:
On Call Duty Officer:
Tel: +44 (0) 870 487 0748 and follow the prompts

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UNIRAS wishes to acknowledge the contributions of US-CERT for the information 
contained in this Briefing. 
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This Briefing contains the information released by the original author. Some 
of the information may have changed since it was released. If the vulnerability 
affects you, it may be prudent to retrieve the advisory from the site of the
original source to ensure that you receive the most current information concerning 
that problem.

Reference to any specific commercial product, process, or service by trade 
name, trademark manufacturer, or otherwise, does not constitute or imply 
its endorsement, recommendation, or favouring by UNIRAS or NISCC.  The views 
and opinions of authors expressed within this notice shall not be used for 
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Neither UNIRAS or NISCC shall also accept responsibility for any errors 
or omissions contained within this briefing notice. In particular, they shall 
not be liable for any loss or damage whatsoever, arising from or in connection 
with the usage of information contained within this notice.

UNIRAS is a member of the Forum of Incident Response and Security Teams (FIRST) 
and has contacts with other international Incident Response Teams (IRTs) in 
order to foster cooperation and coordination in incident prevention, to prompt 
rapid reaction to incidents, and to promote information sharing amongst its 
members and the community at large. 
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<End of UNIRAS Briefing>

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