Microsoft Internet Explorer Cross-Domain Policy Bypass Elevation of Privilege Vulnerability (CVE-2017-0210) Technical Advisory
Executive & SecOps Summary
SECOPS ASSESSMENTMicrosoft Internet Explorer 9, 10, and 11 running on Windows environments
Attackers can bypass the Same-Origin Policy (SOP) to access sensitive information across domains and inject malicious scripts, leading to elevation of privilege
Apply the official Microsoft cumulative security updates immediately, or disable Internet Explorer and transition to modern browsers like Microsoft Edge
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
To mitigate this vulnerability, apply the latest cumulative security updates for Windows. In legacy environments, you can force Windows Update to retrieve and install the necessary patches using the following PowerShell commands:
# Install PSWindowsUpdate module and force update installation
Install-Module PSWindowsUpdate -Force -AllowClobber
Get-WindowsUpdate -AcceptAll -Install -AutoReboot2. Temporary Workaround & Hardening Configuration
If immediate patching is not feasible, disable Internet Explorer via the registry or restrict Active Scripting in the Internet Zone to prevent exploitation.
:: Disable Internet Explorer 11 execution via Registry
reg add 'HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Internet Explorer\Main' /v 'DisableInternetExplorer' /t REG_DWORD /d 1 /f
:: Disable Active Scripting in the Internet Zone (Zone 3)
reg add 'HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\3' /v '1400' /t REG_DWORD /d 3 /f3. Log Audit & IoC Verification Commands
Use the following PowerShell script to audit the installed Internet Explorer version and the file version of mshtml.dll to verify if the system is vulnerable.
# Retrieve Internet Explorer and mshtml.dll version details
$ieVersion = (Get-ItemProperty -Path 'HKLM:\SOFTWARE\Microsoft\Internet Explorer').Version
$mshtmlPath = '$env:SystemRoot\System32\mshtml.dll'
$fileVersion = (Get-Item $mshtmlPath).VersionInfo.FileVersion
Write-Host 'Installed IE Version:' $ieVersion
Write-Host 'mshtml.dll File Version:' $fileVersion
# Ensure the mshtml.dll version is updated beyond the May 2017 release (MS17-044)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 arises because Microsoft Internet Explorer fails to properly enforce cross-domain policies, which are designed to isolate data and scripts between different origins. The Same-Origin Policy (SOP) is a fundamental security mechanism in web browsers that prevents a script loaded from one origin from interacting with resources of another origin. Due to a flaw in how Internet Explorer handles specific internal objects and frame navigation, this boundary can be bypassed, allowing unauthorized cross-domain access and resulting in an elevation of privilege.
2. Exploitation Mechanics & Attack Scenario
An attacker typically exploits this vulnerability by hosting a specially crafted website and enticing a user to visit it (e.g., via phishing emails or malvertising). Once the victim visits the malicious site using Internet Explorer, the attacker's script creates an iframe or a popup window pointing to a targeted, trusted domain (such as a webmail or financial portal). By exploiting the cross-domain validation failure, the attacker's parent page directly accesses the Document Object Model (DOM) of the target domain, enabling them to steal session cookies, read sensitive data, or execute arbitrary actions within the context of the victim's session.
3. Infrastructure & Business Impact
As a vulnerability listed in the CISA KEV catalog, CVE-2017-0210 has been actively exploited in the wild. Successful exploitation allows attackers to hijack active web sessions, bypass multi-factor authentication (MFA) session states, and compromise sensitive corporate web applications. In enterprise environments where legacy Internet Explorer instances are maintained for backward compatibility, this vulnerability poses a severe risk of credential theft and lateral movement within the internal network.
Official Vendor Advisories & References
An elevation of privilege vulnerability exists when Internet Explorer does not properly enforce cross-domain policies, which could allow an attacker to access information from one domain and inject it into another domain, aka "Internet Explorer Elevation of Privilege Vulnerability."
Frequently Asked SecOps Questions (CVE-2017-0210)
FAQQ1. How critical is CVE-2017-0210 and is it actively exploited in the wild?
CVE-2017-0210 is rated CVSS 8.8 (HIGH) with a 30-day EPSS exploitation probability of 22.3%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2017-0210?
Primary impacted vendors include microsoft across internet explorer. Scope summary: All installations of Microsoft Internet Explorer 9, 10, and 11 on supported Windows operating systems without MS17-044 or later cumulative updates
Q3. What temporary mitigations or workarounds exist for CVE-2017-0210 before patching?
[Mitigation] Apply the official Microsoft cumulative security updates immediately, or disable Internet Explorer and transition to modern browsers like Microsoft Edge Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
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