SYMSA-2006-007: Microsoft Office Malformed String Parsing Vulnerability

[research () symantec com]

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                Symantec Vulnerability Research
                http://www.symantec.com/research
                        Security Advisory


Advisory ID   : SYMSA-2006-007
Advisory Title: Microsoft Office Malformed String Parsing
                Vulnerability
Author        : Elia Florio / elia_florio () symantec com
Release Date  : 07-11-2006
Application   : Microsoft Office 2000, Office XP (2002),
                Office 2003
Platform      : Windows
Severity      : Remotely exploitable / User access
Vendor status : Duplicated and verified by Microsoft,
                patch available
CVE Number    : CVE-2006-1540
Reference     : http://www.securityfocus.com/bid/18889


Overview:

        There exists an overflow condition in Microsoft Office
        when a malformed string included in an Office file is
        parsed by any of the affected Office applications.


Details:

        The problem resides in the code of MSO.DLL, a shared
        library used by Office applications, so the vulnerability
        can be exploited using different attack vectors.
        For example, the vulnerability can be exploited using a
        malformed Excel 2003 file. By changing the size of the
        Unicode "Sheet Name" string with an incorrect size, it is
        possible to generate an integer overflow condition. Excel
        2003 will crash while opening the malformed file due to an
        access violation error with an invalid value of
        EAX=0xFFFFFFFC.

        MOV EDX,DWORD PTR DS:[EAX-4]
        ADD EAX,-4
        ADD EDX,4


Vendor Response:

        The above vulnerability was addressed for the affected
        platforms via Microsoft Security Bulletin MS06-38. If
        there are any further questions about this statement,
        please contact secure () microsoft com.


Recommendation:
        Follow your organization's testing procedures before
        applying patches or workarounds.  Customers should apply
        Microsoft's update as soon as possible.


Common Vulnerabilities and Exposures (CVE) Information:

The Common Vulnerabilities and Exposures (CVE) project has assigned
the following names to these issues.  These are candidates for
inclusion in the CVE list (http://cve.mitre.org), which standardizes
names for security problems.

        CVE-2006-1540


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