Microsoft Internet Explorer & Edge mshtml.dll Type Confusion Remote Code Execution (CVE-2017-0037)
Executive & SecOps Summary
SECOPS ASSESSMENTMicrosoft Internet Explorer 10, 11 and legacy Microsoft Edge
Remote attackers can execute arbitrary code and gain full system control when a user visits a maliciously crafted webpage containing specific CSS tokens and JavaScript
Apply the official Microsoft cumulative security updates immediately, or disable Internet Explorer and transition to modern Chromium-based browsers
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Apply the latest cumulative security updates provided by Microsoft. You can force a Windows Update check and installation using the following PowerShell commands:
# Install and use the PSWindowsUpdate module to apply all pending security patches
Install-Module PSWindowsUpdate -Force -Verbose
Get-WindowsUpdate -AcceptAll -Install -AutoReboot2. Temporary Workaround & Hardening Configuration
In legacy environments where immediate patching is not feasible, disable Internet Explorer 11 entirely to mitigate the attack surface:
# Disable Internet Explorer 11 optional feature (requires reboot)
Disable-WindowsOptionalFeature -Online -FeatureName 'Internet-Explorer-Optional-amd64' -NoRestart3. Log Audit & IoC Verification Commands
Verify the file version of mshtml.dll on the system to ensure that the security updates have been successfully applied:
# Check the file version of mshtml.dll
$mshtmlPath = '${env:SystemRoot}\System32\mshtml.dll'
if (Test-Path $mshtmlPath) {
$fileVersion = (Get-Item $mshtmlPath).VersionInfo.FileVersion
Write-Host 'Current mshtml.dll Version:' $fileVersion
} else {
Write-Host 'mshtml.dll is not present in System32.'
}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 is a critical type confusion issue residing within the Layout::MultiColumnBoxBuilder::HandleColumnBreakOnColumnSpanningElement function of mshtml.dll, the rendering engine for Microsoft browsers. When processing multi-column layouts, the rendering engine incorrectly handles specific Cascading Style Sheets (CSS) token sequences combined with JavaScript operations on HTML <th> elements, leading to an incorrect type interpretation of objects in memory.
2. Exploitation Mechanics & Attack Scenario
An attacker can exploit this vulnerability by hosting a specially crafted website that defines a multi-column layout with column-spanning elements and <th> elements. When a vulnerable browser renders this layout, the JavaScript dynamically manipulates the DOM, triggering the type confusion in HandleColumnBreakOnColumnSpanningElement. The engine attempts to access memory using an incorrect object layout, resulting in memory corruption. This allows attackers to bypass modern exploit mitigations and execute arbitrary shellcode within the context of the browser process.
3. Infrastructure & Business Impact
As a vulnerability listed in the CISA KEV catalog, this flaw has been actively exploited in the wild. Successful exploitation allows remote attackers to compromise endpoint systems without user interaction beyond visiting a website. This can serve as an initial entry point into corporate networks, leading to subsequent lateral movement, data exfiltration, and potential ransomware deployment, posing a severe threat to business continuity.
Official Vendor Advisories & References
Microsoft Internet Explorer 10 and 11 and Microsoft Edge have a type confusion issue in the Layout::MultiColumnBoxBuilder::HandleColumnBreakOnColumnSpanningElement function in mshtml.dll, which allows remote attackers to execute arbitrary code via vectors involving a crafted Cascading Style Sheets (CSS) token sequence and crafted JavaScript code that operates on a TH element.
Frequently Asked SecOps Questions (CVE-2017-0037)
FAQQ1. How critical is CVE-2017-0037 and is it actively exploited in the wild?
CVE-2017-0037 is rated CVSS 8.1 (HIGH) with a 30-day EPSS exploitation probability of 80.4%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2017-0037?
Primary impacted vendors include microsoft across internet_explorer, edge. Scope summary: Microsoft Internet Explorer 10, 11 and legacy Microsoft Edge (EdgeHTML-based)
Q3. What temporary mitigations or workarounds exist for CVE-2017-0037 before patching?
[Mitigation] Apply the official Microsoft cumulative security updates immediately, or disable Internet Explorer and transition to modern Chromium-based browsers Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
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