Microsoft Internet Explorer and Edge Information Disclosure Vulnerability (CVE-2016-3351) Technical Advisory
Executive & SecOps Summary
SECOPS ASSESSMENTMicrosoft Internet Explorer 9, 10, and 11, and Microsoft Edge
Remote attackers can determine the presence of specific applications, MIME types, and security software on the host system via crafted web content
Apply official Microsoft security updates (MS16-104, MS16-105) or transition to modern Chromium-based browsers
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Deploy the official cumulative security updates provided by Microsoft (MS16-104 / MS16-105). Use the following PowerShell commands to verify and enforce Windows Updates on enterprise endpoints:
# Ensure Windows Update service is running
Set-Service -Name wuauserv -StartupType Automatic
Start-Service -Name wuauserv
# Check if the relevant security update (e.g., KB3185319) is installed
Get-HotFix | Where-Object { $_.HotFixID -eq 'KB3185319' }2. Temporary Workaround & Hardening Configuration
If legacy browsers cannot be immediately decommissioned, disable Active Scripting or restrict execution permissions for untrusted zones via registry modifications:
# Disable Active Scripting in the Internet Zone (Zone 3) via Registry
$RegistryPath = 'HKCU:\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\3'
Set-ItemProperty -Path $RegistryPath -Name '1400' -Value 33. Log Audit & IoC Verification Commands
Run the following script to audit the current installed versions of Internet Explorer and legacy Edge to identify vulnerable assets:
# Query Internet Explorer version from registry
$IEVersion = (Get-ItemProperty 'HKLM:\SOFTWARE\Microsoft\Internet Explorer').Version
Write-Host 'Installed IE Version:' $IEVersion
# Check for legacy Edge package presence
$EdgeApp = Get-AppxPackage -Name 'Microsoft.MicrosoftEdge'
if ($EdgeApp) {
Write-Host 'Legacy Edge Version:' $EdgeApp.Version
} else {
Write-Host 'Legacy Edge is not present.'
}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
CVE-2016-3351 is an information disclosure vulnerability in Microsoft Internet Explorer 9 through 11 and legacy Microsoft Edge. The root cause lies in how the browsers handle specific MIME types and custom protocol handlers. Due to improper isolation, malicious scripts running in the browser context can query and detect the presence of local applications and security tools installed on the host operating system.
2. Exploitation Mechanics & Attack Scenario
An attacker hosts a specially crafted website containing malicious JavaScript. When a victim visits the site, the script attempts to load specific MIME types or trigger custom URI schemes (e.g., 'mailto:', 'skype:'). By measuring the browser's response behavior or error handling latency, the script determines whether specific software or security agents are installed. This reconnaissance data is typically used to profile the target for subsequent, highly targeted exploits.
3. Infrastructure & Business Impact
This vulnerability is actively exploited in the wild and is cataloged in the CISA KEV list. Successful exploitation allows threat actors to map out the defensive posture of an enterprise endpoint, enabling them to deploy tailored payloads that bypass active endpoint detection and response (EDR) agents, posing a severe risk of initial access and lateral movement.
Official Vendor Advisories & References
Microsoft Internet Explorer 9 through 11 and Microsoft Edge allow remote attackers to obtain sensitive information via a crafted web site, aka "Microsoft Browser Information Disclosure Vulnerability."
Frequently Asked SecOps Questions (CVE-2016-3351)
FAQQ1. How critical is CVE-2016-3351 and is it actively exploited in the wild?
CVE-2016-3351 is rated CVSS 6.5 (MEDIUM) with a 30-day EPSS exploitation probability of 26.5%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2016-3351?
Primary impacted vendors include microsoft across internet_explorer, edge. Scope summary: Microsoft Internet Explorer 9 through 11 and legacy Microsoft Edge
Q3. What temporary mitigations or workarounds exist for CVE-2016-3351 before patching?
[Mitigation] Apply official Microsoft security updates (MS16-104, MS16-105) or 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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