Microsoft Excel Malformed Range Memory Corruption Vulnerability



Date Discovered

December 8, 2005


Microsoft Excel is susceptible to a remote code-execution vulnerability. This issue was originally disclosed through an eBay auction that has since been terminated. This issue is due to the application's failure to properly bounds-check user-supplied input data in the 'Named Range' definition in Excel data files. This results in the corruption of critical memory sections, allowing code execution.

Technologies Affected

  • Avaya Modular Messaging (MAS) 3.0.0
  • Microsoft Excel 2000
  • Microsoft Excel 2000 SP2
  • Microsoft Excel 2000 SP3
  • Microsoft Excel 2000 SR1
  • Microsoft Excel 2002
  • Microsoft Excel 2002 SP1
  • Microsoft Excel 2002 SP2
  • Microsoft Excel 2002 SP3
  • Microsoft Excel 2003
  • Microsoft Excel 2003 SP1
  • Microsoft Excel 2004 for Mac
  • Microsoft Excel 95
  • Microsoft Excel 97
  • Microsoft Excel 97 SR1
  • Microsoft Excel 97 SR2
  • Microsoft Excel Viewer 2003
  • Microsoft Excel x for Mac
  • Nortel Networks Enterprise Network Management System
  • Nortel Networks IP softphone 2050
  • Nortel Networks MCS 5100 3.0.0
  • Nortel Networks MCS 5200 3.0.0
  • Nortel Networks Optivity Telephony Manager (OTM)


Do not accept or execute files from untrusted or unknown sources.
Successful exploitation of this vulnerability requires that the target user open a malicious '.xls' file. Do not accept such files from untrusted sources.

Run all software as a nonprivileged user with minimal access rights.
Any code that is executed would run with the privileges of the user who opened the document. Do not use applications such as this on critical hosts. Ensure that users are logged in as accounts with minimal privileges. This may limit the immediate impact of a successful attack.

Microsoft has released fixes to address this vulnerability in supported versions of the affected software. Please see the referenced vendor advisories for further information.



Discovery is credited to 'fearwall'. Microsoft also credits FelicioX and Peter Winter-Smith for the discovery of this vulnerability.

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