CVE-2016-3349 in Windows
Summary
by MITRE
The kernel-mode drivers in Microsoft Windows 8.1, Windows Server 2012 Gold and R2, Windows RT 8.1, and Windows 10 Gold and 1511 allow local users to gain privileges via a crafted application, aka "Win32k Elevation of Privilege Vulnerability."
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Analysis
by VulDB Data Team • 09/16/2022
The Win32k Elevation of Privilege Vulnerability represents a critical security flaw in Microsoft Windows kernel-mode drivers that affects multiple operating system versions including Windows 8.1, Windows Server 2012 Gold and R2, Windows RT 8.1, and Windows 10 Gold and 1511. This vulnerability resides within the win32k.sys driver which manages user-mode graphics components and system-level windowing functions. The flaw enables local attackers with standard user privileges to execute arbitrary code with elevated system-level permissions, effectively bypassing standard security boundaries that normally protect the operating system from unauthorized access. The vulnerability stems from improper validation of user-supplied data within the kernel-mode driver, creating a path for privilege escalation attacks that can result in complete system compromise.
The technical exploitation of this vulnerability occurs through crafted applications that manipulate the win32k.sys driver's handling of graphics-related system calls. Attackers can leverage the flaw by submitting malicious input to graphics functions that are processed within kernel space, where the driver fails to properly validate the data before processing. This improper validation allows attackers to manipulate memory structures and execute code with kernel-level privileges. The vulnerability specifically relates to how the driver handles certain graphics objects and window management operations, creating opportunities for attackers to overwrite critical system memory or manipulate execution flow. According to CWE classification, this vulnerability maps to CWE-121, which describes stack-based buffer overflow conditions, and CWE-125, which covers out-of-bounds read conditions that can lead to privilege escalation.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass complete system compromise and potential data exfiltration. Once an attacker successfully exploits this vulnerability, they gain unrestricted access to the entire system, including the ability to install malicious software, modify system files, access sensitive data, and establish persistent backdoors. The vulnerability's presence in multiple Windows versions makes it particularly dangerous as it affects a broad user base including enterprise environments, government systems, and individual users. The local nature of the exploit means that attackers do not require network connectivity or remote access capabilities, making the vulnerability particularly concerning for environments where physical access or social engineering attacks are possible. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques under T1068 and defense evasion tactics under T1070, as attackers can use the elevated privileges to hide their malicious activities and maintain persistence.
Microsoft addressed this vulnerability through security updates that corrected the improper validation within the win32k.sys driver. Organizations should implement immediate patch management procedures to mitigate the risk, as the vulnerability was actively exploited in the wild. The recommended mitigation strategy involves deploying the appropriate security updates from Microsoft's security bulletin MS16-051, which specifically addresses this vulnerability. Additionally, system administrators should implement principle of least privilege controls, disable unnecessary graphics functionality where possible, and monitor for suspicious system behavior that might indicate exploitation attempts. The vulnerability highlights the critical importance of kernel-mode security and demonstrates how flaws in system-level components can have catastrophic consequences for overall system security.