CVE-2016-7226 in Windows
Summary
by MITRE
Virtual Hard Disk Driver in Windows 10 Gold, 1511, and 1607 and Windows Server 2016 does not properly restrict access to files, which allows local users to gain privileges via a crafted application, aka "VHD Driver Elevation of Privilege Vulnerability."
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Analysis
by VulDB Data Team • 05/09/2025
The CVE-2016-7226 vulnerability represents a critical elevation of privilege flaw within the Virtual Hard Disk Driver component of Microsoft Windows operating systems. This vulnerability affects Windows 10 versions 1511 and 1607, Windows 10 Gold, and Windows Server 2016, creating a significant security risk for systems running these versions. The flaw resides in how the VHD driver handles file access controls, specifically failing to properly restrict access to system resources during virtual disk operations. Attackers can exploit this weakness by crafting malicious applications that manipulate the driver's file handling mechanisms to escalate their privileges from standard user level to administrative privileges. This vulnerability directly maps to CWE-284, which describes improper access control issues, and represents a classic example of a privilege escalation vulnerability that undermines the fundamental security model of the operating system.
The technical exploitation of this vulnerability occurs when a local attacker crafts a malicious application that leverages the improper file access restrictions within the Virtual Hard Disk Driver. The flaw allows an attacker to manipulate how the driver processes virtual disk files, potentially enabling them to access restricted system resources or modify protected files. When the vulnerable driver processes a crafted VHD file, it fails to validate access permissions properly, allowing unauthorized operations that should be restricted to privileged processes. This improper access control manifests during normal file operations within virtualized environments where the driver is responsible for managing virtual disk images. The vulnerability's impact is particularly concerning because it operates at the kernel level, where the driver executes with elevated privileges, making the privilege escalation particularly effective and difficult to detect through standard security monitoring.
The operational impact of CVE-2016-7226 extends beyond simple privilege escalation, as it provides attackers with a persistent foothold within affected systems. Once successfully exploited, attackers can gain administrative access to the compromised machine, enabling them to install malware, modify system configurations, steal sensitive data, or establish backdoors for continued access. The vulnerability affects systems where virtualization is actively used, making it particularly dangerous in enterprise environments where virtual machines and virtualized applications are common. This flaw aligns with ATT&CK technique T1068, which covers 'Exploitation for Privilege Escalation', and represents a classic path for attackers to move from initial access to system control. The vulnerability's presence in Windows Server 2016 also means that enterprise environments running server virtualization technologies face significant risk, as this represents a potential attack vector for lateral movement and persistent access within network infrastructure.
Organizations should implement immediate mitigations including applying the relevant Microsoft security updates and patches that address the VHD driver access control issues. System administrators should also consider implementing additional security controls such as disabling unnecessary virtualization features, monitoring for suspicious file access patterns, and ensuring proper application whitelisting policies are in place. The vulnerability demonstrates the importance of maintaining up-to-date system patches and highlights the risks associated with virtualization components in operating systems. Security teams should monitor for exploitation attempts through endpoint detection and response tools, particularly looking for unusual file access or virtual disk manipulation activities. Additionally, implementing principle of least privilege configurations and reducing local user account permissions can help limit the potential impact if exploitation occurs, though the vulnerability itself allows for complete privilege escalation regardless of these controls.