Microsoft Internet Explorer mshtml.dll Use-After-Free Remote Code Execution Vulnerability (CVE-2012-4969)
Executive & SecOps Summary
SECOPS ASSESSMENTMicrosoft Internet Explorer versions 6, 7, 8, and 9
Remote attackers can execute arbitrary code with the privileges of the current user by enticing a user to visit a specially crafted website
Apply the official cumulative security update (MS12-063), transition to a modern supported browser, or apply the official Fix it solution
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
The primary remediation is to upgrade to a modern, supported web browser. For legacy environments requiring Internet Explorer, apply the MS12-063 cumulative security update. You can verify the current version of mshtml.dll using the following PowerShell command:
# Check the file version of mshtml.dll to ensure patch compliance
Get-ItemProperty -Path 'C:\Windows\System32\mshtml.dll' | Select-Object -Property VersionInfo | Format-List2. Temporary Workaround & Hardening Configuration
If patching cannot be immediately deployed, configure the registry to disable Active Scripting in the Internet Security Zone or prompt before running, which mitigates the primary vector of exploitation.
Windows Registry Editor Version 5.00
; Disable Active Scripting in the Internet Zone (Zone 3)
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\3]
"1400"=dword:000000033. Log Audit & IoC Verification Commands
To identify potential exploitation attempts or browser crashes related to this vulnerability, audit the Windows Application Event Logs for crashes originating from mshtml.dll:
# Query Application Event Logs for Event ID 1000 involving mshtml.dll
wevtutil qe Application /q:"*[System[Provider[@Name='Application Error'] and (EventID=1000)]]" /f:text | findstr /i "mshtml.dll"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
A Use-After-Free (UAF) vulnerability exists in the CMshtmlEd::Exec function within mshtml.dll in Microsoft Internet Explorer. The root cause lies in the improper handling of objects in memory during the execution of specific HTML editing commands (execCommand). When a specific DOM element is deleted or modified, the memory allocated for the object is freed, but the reference pointer is not cleared, leaving a dangling pointer that can be subsequently manipulated.
2. Exploitation Mechanics & Attack Scenario
An attacker exploits this vulnerability by hosting a malicious web page containing crafted HTML and JavaScript. When a victim visits the site, the script triggers the deletion of an object and immediately invokes document.execCommand, forcing CMshtmlEd::Exec to access the freed memory address. By utilizing heap spraying techniques, the attacker fills the freed memory space with controlled payloads (shellcode), hijacking the execution flow of the browser process to bypass security mitigations and execute arbitrary commands.
3. Infrastructure & Business Impact
This vulnerability was actively exploited in the wild as a zero-day threat. Successful exploitation grants the attacker the same privileges as the active user. If the compromised user has administrative rights, the attacker can gain complete control of the host system, install malicious software, modify data, or pivot deeper into the corporate network, posing a severe threat to enterprise infrastructure.
Official Vendor Advisories & References
Use-after-free vulnerability in the CMshtmlEd::Exec function in mshtml.dll in Microsoft Internet Explorer 6 through 9 allows remote attackers to execute arbitrary code via a crafted web site, as exploited in the wild in September 2012.
Frequently Asked SecOps Questions (CVE-2012-4969)
FAQQ1. How critical is CVE-2012-4969 and is it actively exploited in the wild?
CVE-2012-4969 is rated CVSS 8.1 (HIGH) with a 30-day EPSS exploitation probability of 80.3%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2012-4969?
Primary impacted vendors include microsoft across internet_explorer. Scope summary: Microsoft Internet Explorer versions 6 through 9 utilizing mshtml.dll
Q3. What temporary mitigations or workarounds exist for CVE-2012-4969 before patching?
[Mitigation] Apply the official cumulative security update (MS12-063), transition to a modern supported browser, or apply the official Fix it solution Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
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