Fortinet Security Research Team (FSRT) has discovered an Improper Memory Access Vulnerability in Microsoft Excel.


A remote Improper Memory Access Vulnerability exists in Microsoft Excel which could allow an attacker who successfully exploited this vulnerability to take complete control of the affected system.


  • Critical

Affected Software:

  • Microsoft Office 2000 Service Pack 3
    • Microsoft Excel 2000
  • Microsoft Office XP Service Pack 3
    • Microsoft Excel 2002
  • Microsoft Office 2003 Service Pack 2
    • Microsoft Excel 2003
    • Microsoft Office Excel Viewer 2003
  • Microsoft Works Suites:
    • Microsoft Works Suite 2004 (same as the Microsoft Excel 2002 update)
    • Microsoft Works Suite 2005 (same as the Microsoft Excel 2002 update)
    • Microsoft Works Suite 2006 (same as the Microsoft Excel 2002 update)
  • Microsoft Office 2004 for Mac
  • Microsoft Office v. X for Mac

Non-Affected Software:

  • 2007 Microsoft Office system
    • Microsoft Office Excel 2007

Additional Information:

A remote attacker could construct a .xls file and put it on a controlled website. When the user opens the .xls file with the Microsoft Internet Explorer, the browser will automatically call Microsoft Excel to open the .xls file. And if specially crafted, this will cause Microsoft Excel to crash; then, the .xls may allow the attacker to execute arbitrary code.

This vulnerability is due to Microsoft Excel's manipulation of specific opcode.


  • Microsoft Office users should apply the update provided by Microsoft.
  • Do not open Microsoft Office Excel files from untrusted source.


  • Jie Ma of Fortinet Security Research Team