CVE-2006-2492

What is Microsoft Word?

Microsoft Word is the world's most widely used word processing application, part of the Microsoft Office suite. Its document format (.DOC, and later .DOCX) has been the de facto standard for business documents for three decades. Because Word is ubiquitous in enterprise environments and documents are routinely shared via email, malicious Word documents have been a primary delivery mechanism for malware and targeted attacks since the mid-1990s. Microsoft Word's rich feature set — embedded objects, macros, OLE linking, and complex rendering code — created a large attack surface that has yielded dozens of security vulnerabilities over its history.

Overview

CVE-2006-2492 is a high-severity remote code execution vulnerability (CWE-120, CVSS 8.8) in Microsoft Word. A malformed object pointer in a specially crafted Word document (.DOC file) allowed attackers to execute arbitrary code when the document was opened in the victim's Word installation. The vulnerability was actively exploited as a zero-day — malicious Word documents were circulating in targeted attacks before Microsoft released its patch. Microsoft issued the fix in Security Bulletin MS06-027 (June 2006 Patch Tuesday). CISA added to KEV in June 2022.

Affected Versions

Technical Details

The vulnerability (CWE-120: Buffer Copy without Checking Size of Input) exists in how Microsoft Word processes certain object types embedded in .DOC files. Word documents can contain embedded OLE objects, linked objects, and various structured data elements within the binary .DOC format. In the vulnerable code path, Word read an object pointer value directly from the document file without validation and used it to access a memory structure.

A malformed document could:

1. Contain a crafted object descriptor with an invalid or attacker-controlled pointer value
2. Word's parser would dereference the malformed pointer when processing the object structure
3. If the pointer could be directed to attacker-controlled heap memory (via heap spraying or other memory manipulation), arbitrary code execution followed in the security context of the user running Word

Because Word typically runs as the logged-in user, successful exploitation gave the attacker the same privileges as the victim — including full desktop access on single-user workstations.

The CVSS "Network" attack vector reflects the practical delivery mechanism: malicious .DOC files delivered as email attachments and served from web pages, even though the final exploit occurs locally when the file is opened.

Discovery

Discovered and exploited in the wild before public disclosure — a true zero-day. Microsoft was alerted through customer incident reports of malicious Word documents being used in targeted attacks. The May 2006 disclosure acknowledged active exploitation. This was part of a significant increase in targeted "document malware" attacks seen in 2005–2007, where state-sponsored and criminal actors pivoted from network worms to document-based spear phishing for targeted intrusions.

Exploitation Context

The 2006 document zero-day era established patterns that persist in attacks today:

• Targeted spear phishing: Malicious .DOC files sent to specific individuals — executives, researchers, government officials — with contextually relevant content (conference invites, contract documents, policy papers) to increase the likelihood of opening
• State-sponsored intrusions: Zero-day Word exploits in this period were associated with espionage campaigns, particularly attributed to Chinese and other nation-state actors targeting defense contractors, government agencies, and research institutions
• Drive-by exploitation: Malicious Word documents hosted on compromised websites triggered for visitors — especially effective against organizations whose users routinely downloaded Word documents from external sources
• Legacy exposure: The 2022 CISA KEV addition reflects that some organizations still running Office 2000/2002/2003 were encountering this vulnerability in attack chains, particularly in environments where older Office versions persisted on specialized systems

Remediation

1. Apply MS06-027 (June 2006 Patch Tuesday): For any remaining systems running Office 2000, XP, or 2003, apply this update immediately.
2. Upgrade to a modern Office version: Office 2000, 2002, and 2003 are long past end-of-life and receive no security updates. Upgrade to a supported Microsoft 365 or Office 2019/2021 version.
3. Enable Protected View: Modern Office versions open downloaded documents in Protected View (sandbox mode), which prevents document-triggered exploits from executing. Ensure Protected View is enabled for documents from internet and email sources.
4. Block .DOC legacy format: Consider blocking legacy binary .DOC files at email gateways if not required, forcing use of the more constrained .DOCX format.
5. Email attachment scanning: Deploy email security scanning to detect malicious documents before they reach end users.