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Security Services

Microsoft Office MsoPvAllocCore DoS Vulnerability



Microsoft Excel is the spreadsheet application within Microsoft Office.


Remote exploitation of a denial of service vulnerability in Microsoft Corp.'s Office suite could allow an attacker to crash an Office application. The vulnerability occurs when the Office custom heap allocator, the MSO allocator, is asked for a 0-sized allocation request. When this occurs, the allocator returns a pointer to an unmapped area of memory. This can result in an application crash if the pointer is accessed.


Exploitation of this vulnerability results in the execution of arbitrary code with the privileges of the user opening the file. To exploit this vulnerability, an attacker needs to convince a user to open a malicious file. Attackers typically accomplish this by e-mailing a targeted user the file or hosting the file on a Web page. Note that attackers cannot exploit Office file format vulnerabilities in a drive-by manner; at a minimum, a targeted user must click an "open" dialog or choose to view an attachment.


The following Microsoft products are vulnerable:

  • Microsoft Excel 2003 Service Pack 3
  • Microsoft Excel 2007 Service Pack 2
  • Microsoft Excel 2007 Service Pack 3
  • Microsoft Excel 2010 Service Pack 1 (32-bit editions)
  • Microsoft Excel 2010 Service Pack 1 (64-bit editions)
  • Microsoft Excel Viwer
  • Microsoft Office Compatibility Pack Service Pack 2
  • Microsoft Office Compatibility Pack Service Pack 3


The vulnerability occurs in the core parsing code of Excel, which cannot be disabled; however, it is possible to disable the opening of the older binary format files by using MOICE to convert the file to the newer XML-based format.


Microsoft Corp. has released patches which addresses this issue. For more information, consult their advisory at the following URL:


The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2012-1886 to this issue. This is a candidate for inclusion in the CVE list (, which standardizes names for security problems.


03/21/2012 Initial Vendor Notification
03/21/2012 Initial Vendor Reply
11/13/2012 Coordinated Public Disclosure


The discoverer of this vulnerability wishes to remain anonymous.

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Copyright © 2012 Verisign, Inc.

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