Microsoft Windows Mount Manager Elevation of Privilege Vulnerability (CVE-2015-1769, MS15-085)
Executive & SecOps Summary
SECOPS ASSESSMENTWindows Vista, 7, 8, 8.1, 10, and Windows Server 2008, 2012 legacy environments
A physically proximate attacker can execute arbitrary code with SYSTEM privileges by connecting a crafted USB device, leading to full system compromise
Apply the MS15-085 security update immediately and restrict unauthorized USB storage devices via Group Policy
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Apply the official MS15-085 security update. For legacy systems, use the following PowerShell commands to force Windows Update to retrieve and install the necessary security patches.
# Install and run Windows Update module to apply MS15-085 and cumulative patches
Install-Module PSWindowsUpdate -Force -Verbose
Get-WindowsUpdate -AcceptAll -Install -AutoReboot2. Temporary Workaround & Hardening Configuration
If immediate patching is not feasible, disable the USB Storage driver and AutoRun features to mitigate the physical attack vector.
# Disable the USB Storage (USBSTOR) service via Registry
Set-ItemProperty -Path 'HKLM:\SYSTEM\CurrentControlSet\Services\USBSTOR' -Name 'Start' -Value 4
# Disable AutoRun for all drive types to prevent automatic mounting exploits
New-ItemProperty -Path 'HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Explorer' -Name 'NoDriveTypeAutoRun' -PropertyType DWord -Value 255 -Force3. Log Audit & IoC Verification Commands
Audit the system for recently connected USB devices and verify the file version of the Mount Manager driver (mountmgr.sys) to ensure the patch is active.
# Audit registry for historically connected USB storage devices
Get-ItemProperty -Path 'HKLM:\SYSTEM\CurrentControlSet\Enum\USBSTOR\*\*' | Select-Object FriendlyName, HardwareID, Mfg
# Verify the file version of the Mount Manager driver
Get-Item -Path 'C:\Windows\System32\drivers\mountmgr.sys' | Select-Object -ExpandProperty VersionInfoBlock 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 (CVE-2015-1769) is a logical flaw in how the Microsoft Windows Mount Manager handles symbolic links (symlinks). The Mount Manager is responsible for detecting newly connected volumes and assigning appropriate drive letters or mount paths. When a malicious device containing crafted symlinks is connected, the Mount Manager fails to properly validate the symbolic link paths, allowing the system to traverse unauthorized directories under elevated contexts.
2. Exploitation Mechanics & Attack Scenario
An attacker with physical access prepares a malicious USB mass storage device configured with a specially crafted partition table and symbolic links. Upon inserting the USB device into a target machine, the Windows Mount Manager automatically processes and mounts the volume. During this automated parsing, a high-privilege system service or kernel component follows the malicious symlink to a target system directory, enabling the execution of arbitrary binaries or scripts with SYSTEM privileges.
3. Infrastructure & Business Impact
As a vulnerability listed in the CISA KEV catalog, this flaw has been actively exploited in the wild. It poses a severe threat to physically accessible endpoints such as kiosks, ATMs, and corporate workstations. Successful exploitation bypasses standard operating system access controls, allowing attackers to establish persistence, dump credentials, and deploy ransomware across the internal network.
Official Vendor Advisories & References
Mount Manager in Microsoft Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8, Windows 8.1, Windows Server 2012 Gold and R2, Windows RT Gold and 8.1, and Windows 10 mishandles symlinks, which allows physically proximate attackers to execute arbitrary code by connecting a crafted USB device, aka "Mount Manager Elevation of Privilege Vulnerability."
Frequently Asked SecOps Questions (CVE-2015-1769)
FAQQ1. How critical is CVE-2015-1769 and is it actively exploited in the wild?
CVE-2015-1769 is rated CVSS 6.6 (MEDIUM) with a 30-day EPSS exploitation probability of 4.1%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2015-1769?
Primary impacted vendors include microsoft across windows, windows_server. Scope summary: Windows Vista SP2, Windows Server 2008 SP2/R2 SP1, Windows 7 SP1, Windows 8/8.1, Windows Server 2012 Gold/R2, Windows RT Gold/8.1, Windows 10
Q3. What temporary mitigations or workarounds exist for CVE-2015-1769 before patching?
[Mitigation] Apply the MS15-085 security update immediately and restrict unauthorized USB storage devices via Group Policy Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
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