Vulnerability Note VU#910998

Microsoft Windows kernel fails to properly handle invalid opcodes used in DOS emulation

Original Release date: 13 Oct 2004 | Last revised: 13 Oct 2004


A vulnerability in the way the Microsoft Windows kernel handles invalid opcodes used in DOS emulation could allow a local attacker to gain elevated privileges on a vulnerable system.


The Virtual DOS Machine (VDM) provides support for 16-bit legacy operations and applications. For instance, a VDM is started when a user executes a MS-DOS application. The Windows kernel is responsible for handling 16-bit code executed inside a VDM. There is a vulnerability in the way the Windows kernel validates memory locations allocated to a VDM. After processing an invalid opcode byte sequence, the kernel fails to validate the memory address where execution should be transferred allowing an attacker to redirect this execution to arbitrary locations in memory. Exploitation of this vulnerability could allow a local, authenticated attacker to execute arbitrary code on an affected system with kernel privileges.

Microsoft reports that this is not the same vulnerability described in MS04-011.


A local, authenticated attacker could execute arbitrary code with kernel privileges on an affected system.


Apply Patch
Microsoft has provided a patch to address this vulnerability. For a list of affected versions and details on obtaining the patch, please refer to Microsoft Security Bulletin MS04-032.

Systems Affected (Learn More)

VendorStatusDate NotifiedDate Updated
Microsoft CorporationAffected-13 Oct 2004
If you are a vendor and your product is affected, let us know.

CVSS Metrics (Learn More)

Group Score Vector
Base N/A N/A
Temporal N/A N/A
Environmental N/A N/A



This vulnerability was reported by Microsoft. Microsoft credits eEye Digital Security for discovering the vulnerability.

This document was written by Damon Morda based on information contained in the eEye Advisory.

Other Information

  • CVE IDs: CAN-2004-0208
  • Date Public: 12 Oct 2004
  • Date First Published: 13 Oct 2004
  • Date Last Updated: 13 Oct 2004
  • Severity Metric: 10.69
  • Document Revision: 12


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