Microsoft Internet Explorer ASLR Bypass Vulnerability (CVE-2015-0071, MS15-009) Technical Analysis and Mitigation Guide
Executive & SecOps Summary
SECOPS ASSESSMENTMicrosoft Internet Explorer 9, 10, and 11
Attackers can bypass Address Space Layout Randomization (ASLR) protections via crafted web content, significantly increasing the success rate of subsequent Remote Code Execution (RCE) attacks
Apply the MS15-009 cumulative security update, transition to Microsoft Edge, and enforce system-wide exploit mitigations (Force ASLR)
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
The primary remediation is to apply the MS15-009 cumulative security update. For legacy systems where Internet Explorer is still present, you can force the installation of the required security updates using PowerShell:
# Install Windows Update module and apply the cumulative security update
Install-Module PSWindowsUpdate -Force -Verbose
Get-WindowsUpdate -KBArticleID KB3034196 -Install -AcceptAll -AutoReboot2. Temporary Workaround & Hardening Configuration
If immediate patching is not feasible, enforce system-wide ASLR and DEP mitigations for the Internet Explorer process using the registry to mitigate exploitation attempts:
:: Force ASLR and enable mitigation options for Internet Explorer via Registry
reg add 'HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\iexplore.exe' /v MitigationOptions /t REG_QWORD /d 0x0000000000000101 /f3. Log Audit & IoC Verification Commands
You can verify the patch level of your system by checking the file version of mshtml.dll, which is heavily modified by the MS15-009 update:
# Check the file version of mshtml.dll to verify patch status
$targetPath = 'C:\Windows\System32\mshtml.dll'
if (Test-Path $targetPath) {
$fileVersion = (Get-Item $targetPath).VersionInfo.FileVersion
Write-Output 'Current mshtml.dll version: ' + $fileVersion
} else {
Write-Output 'mshtml.dll is not present on this system.'
}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-2015-0071 is an Address Space Layout Randomization (ASLR) bypass vulnerability affecting Microsoft Internet Explorer versions 9 through 11. The root cause lies in the way the browser engine handles memory layout and object pointers in memory. Due to improper isolation or disclosure of memory addresses, an attacker can predict the memory locations of loaded modules and system DLLs.
2. Exploitation Mechanics & Attack Scenario
An attacker exploits this vulnerability by hosting a specially crafted website containing malicious JavaScript or ActiveX controls. When a target user visits the site, the script triggers a memory disclosure condition that leaks specific pointers. By calculating the base addresses of critical libraries (such as mshtml.dll or kernel32.dll), the attacker bypasses ASLR. This leaked layout information is then used to construct a Return-Oriented Programming (ROP) chain to bypass Data Execution Prevention (DEP) and execute arbitrary shellcode.
3. Infrastructure & Business Impact
As this vulnerability is cataloged in CISA's Known Exploited Vulnerabilities (KEV) list, it has been actively exploited in targeted campaigns. While an ASLR bypass does not directly execute code on its own, it serves as a critical stepping stone for reliable remote code execution. Successful exploitation can lead to complete endpoint compromise, lateral movement within corporate networks, and deployment of ransomware.
Official Vendor Advisories & References
Microsoft Internet Explorer 9 through 11 allows remote attackers to bypass the ASLR protection mechanism via a crafted web site, aka "Internet Explorer ASLR Bypass Vulnerability."
Frequently Asked SecOps Questions (CVE-2015-0071)
FAQQ1. How critical is CVE-2015-0071 and is it actively exploited in the wild?
CVE-2015-0071 is rated CVSS 6.5 (MEDIUM) with a 30-day EPSS exploitation probability of 33.6%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2015-0071?
Primary impacted vendors include microsoft across internet explorer. Scope summary: Microsoft Internet Explorer 9, 10, and 11 running on supported Windows operating systems (Windows Vista, 7, 8, 8.1, Server 2008/2012)
Q3. What temporary mitigations or workarounds exist for CVE-2015-0071 before patching?
[Mitigation] Apply the MS15-009 cumulative security update, transition to Microsoft Edge, and enforce system-wide exploit mitigations (Force ASLR) Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
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