Microsoft Office Word Stack-Based Buffer Overflow Vulnerability (CVE-2009-0563) Technical Advisory
Executive & SecOps Summary
SECOPS ASSESSMENTMicrosoft Office Word 2002/2003/2007, Office for Mac 2004/2008, Word Viewer, and Compatibility Pack
Remote attackers can execute arbitrary code via a specially crafted Word document containing an invalid length field in a tag
Apply the official Microsoft security update (MS09-027) immediately and restrict execution of untrusted document files
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Deploy the official Microsoft Security Update MS09-027. For managed Windows environments, you can query and trigger the installation of missing security updates using PowerShell:
# Query Windows Update for missing security patches
$UpdateSession = New-Object -ComObject Microsoft.Update.Session
$UpdateSearcher = $UpdateSession.CreateUpdateSearcher()
$SearchResult = $UpdateSearcher.Search('IsInstalled=0 and Type=Software')
# Filter for MS09-027 related updates or general Office security updates
$OfficeUpdates = $SearchResult.Updates | Where-Object { $_.Title -like '*Office*' -or $_.Title -like '*Word*' }
if ($OfficeUpdates) {
Write-Host 'Pending Office Security Updates found. Please apply patches immediately.' -ForegroundColor Red
$OfficeUpdates | Select-Object Title, KBArticleIDs
} else {
Write-Host 'No pending Office updates detected.' -ForegroundColor Green
}2. Temporary Workaround & Hardening Configuration
If immediate patching is not feasible, enforce File Block policies via the registry to prevent Word from opening legacy binary file formats or untrusted converters:
Windows Registry Editor Version 5.00
; Block opening of older Word document formats in Word 2007
[HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\Word\Security\FileOpenBlock]
"FilesBeforeV9"=dword:00000002
"Converters"=dword:000000023. Log Audit & IoC Verification Commands
Verify the installed version of the Microsoft Word executable (winword.exe) to identify if the system is running a vulnerable version:
# Retrieve and verify the file version of winword.exe
$WordPath = (Get-ItemProperty -Path 'HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths\Winword.exe' -ErrorAction SilentlyContinue).'(Default)'
if ($WordPath) {
$VersionInfo = (Get-Item $WordPath).VersionInfo
Write-Host "Product: $($VersionInfo.ProductName)"
Write-Host "File Version: $($VersionInfo.FileVersion)"
# Compare the version against the patched baselines specified in MS09-027
} else {
Write-Host 'Microsoft Word is not installed or the path could not be resolved.'
}Block Kernel Privilege Escalation & Ransomware Payloads Before You Can Reboot
Protect unpatched Windows, Linux, and macOS workloads against in-memory exploitation and lateral movement with autonomous EDR.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2009-0563) is a stack-based buffer overflow (CWE-787) residing in the parsing engine of Microsoft Office Word and associated file converters. The root cause lies in the improper validation of length fields within specific tags of Word document structures. When the application parses a crafted tag with an invalid, excessively large length field, it copies data beyond the allocated stack buffer, leading to memory corruption.
2. Exploitation Mechanics & Attack Scenario
An attacker exploits this vulnerability by constructing a malicious Word document (.doc or Open XML format) containing a malformed tag with an invalid length attribute. This document is typically delivered via spear-phishing emails or malicious web downloads. Upon opening the document, the vulnerable parser processes the malformed tag, triggering a stack overflow that overwrites the return address of the active stack frame. This allows the attacker to redirect execution flow to arbitrary shellcode within the context of the current user.
3. Infrastructure & Business Impact
As a high-severity vulnerability listed in the CISA KEV catalog with a high EPSS score, this flaw has been actively exploited in the wild. Successful exploitation grants the attacker the same privileges as the local user. In an enterprise environment, this can lead to initial access, lateral movement, sensitive data exfiltration, and full endpoint compromise, posing a severe threat to business operations.
Official Vendor Advisories & References
Stack-based buffer overflow in Microsoft Office Word 2002 SP3, 2003 SP3, and 2007 SP1 and SP2; Microsoft Office for Mac 2004 and 2008; Open XML File Format Converter for Mac; Microsoft Office Word Viewer 2003 SP3; Microsoft Office Word Viewer; and Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats SP1 and SP2 allows remote attackers to execute arbitrary code via a Word document with a crafted tag containing an invalid length field, aka "Word Buffer Overflow Vulnerability."
Frequently Asked SecOps Questions (CVE-2009-0563)
FAQQ1. How critical is CVE-2009-0563 and is it actively exploited in the wild?
CVE-2009-0563 is rated CVSS 7.8 (HIGH) with a 30-day EPSS exploitation probability of 59.6%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2009-0563?
Primary impacted vendors include microsoft across office, word, office_for_mac, word_viewer, office_compatibility_pack. Scope summary: Microsoft Office Word 2002 SP3, 2003 SP3, 2007 SP1/SP2, Office for Mac 2004/2008, Open XML File Format Converter for Mac, Word Viewer 2003 SP3, Word Viewer, Office Compatibility Pack SP1/SP2
Q3. What temporary mitigations or workarounds exist for CVE-2009-0563 before patching?
[Mitigation] Apply the official Microsoft security update (MS09-027) immediately and restrict execution of untrusted document files Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
Generate an Internal Engineering Notice or CISO Report for CVE-2009-0563
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