Date Discovered

December 10, 2006


Microsoft Word is prone to a remote code-execution vulnerability. An attacker could exploit this issue by enticing a victim to open a malicious Word file. If the attack is successful, the attacker may be able to execute arbitrary code in the context of the currently logged-in user. This issue is being actively exploited in the wild in limited targeted attacks. Note that this issue is distinct from BID 21451 (Microsoft Word Malformed String Arbitrary Remote Code Execution Vulnerability). Update – February 1, 2007: A new variant of this issue has been detected in the wild. Please see the references for more information about this variant, which is referred to as Trojan.Mdropper.X. Note that Trojan.Mdropper.X was previously thought to be targeting a new vulnerability that was described in BID 22328 (Microsoft Word 2003 Unspecified Code Execution Vulnerability). However, further analysis and reports have revealed that it is not distinct from this vulnerability. BID 22328 has been retired.

Technologies Affected

  • Microsoft Office 2000
  • Microsoft Office 2000 Chinese Version
  • Microsoft Office 2000 Japanese Version
  • Microsoft Office 2000 Korean Version
  • Microsoft Office 2000 SP1
  • Microsoft Office 2000 SP2
  • Microsoft Office 2000 SP2
  • Microsoft Office 2000 SP2
  • Microsoft Office 2000 SP3
  • Microsoft Office 2003
  • Microsoft Office 2003 SP1
  • Microsoft Office 2003 SP2
  • Microsoft Office 2003 SP3
  • Microsoft Office 2004 for Mac
  • Microsoft Office XP
  • Microsoft Office XP Developer Edition
  • Microsoft Office XP SP1
  • Microsoft Office XP SP2
  • Microsoft Office XP SP3
  • Microsoft Word 2000
  • Microsoft Word 2000 Chinese Version
  • Microsoft Word 2000 Japanese Version
  • Microsoft Word 2000 Korean Version
  • Microsoft Word 2000 SP2
  • Microsoft Word 2000 SP3
  • Microsoft Word 2000 SR1
  • Microsoft Word 2000 Sr1a
  • Microsoft Word 2002
  • Microsoft Word 2002 SP1
  • Microsoft Word 2002 SP2
  • Microsoft Word 2002 SP3
  • Microsoft Word 2003
  • Microsoft Word 2004 for Mac
  • Microsoft Word Viewer 2003
  • Microsoft Word Viewer 2003
  • Microsoft Word X for Mac
  • Microsoft Works Suite 2004
  • Microsoft Works Suite 2005
  • Microsoft Works Suite 2006


Deploy network intrusion detection systems to monitor network traffic for malicious activity.
Deploy NIDS to monitor network traffic for signs of suspicious or anomalous activity. This may help detect malicious actions that an attacker may take after successfully exploiting vulnerabilities in applications. Review all applicable logs regularly.

Do not accept or execute files from untrusted or unknown sources.
Users should never accept files from untrusted or unknown sources, because they may be malicious in nature. Avoid opening email attachments from unknown or questionable sources.

Do not follow links provided by unknown or untrusted sources.
Users should avoid websites of questionable integrity. Never follow links supplied by unknown or untrusted sources.

Implement multiple redundant layers of security.
Since this issue may be leveraged to execute code, we recommend memory-protection schemes, such as non-executable stack/heap configurations and randomly mapped memory segments. This tactic may complicate exploit attempts of memory-corruption vulnerabilities.

Microsoft has released details regarding updates that address this issue in supported versions of affected applications.



This issue was discovered by McAfee.

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