CVE-2016-8819 in GPU Driver
Summary
by MITRE
All versions of NVIDIA Windows GPU Display Driver contain a vulnerability in the kernel mode layer (nvlddmkm.sys) handler for DxgkDdiEscape where a handle to a kernel object may be returned to the user, leading to possible denial of service or escalation of privileges.
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Analysis
by VulDB Data Team • 07/09/2019
The vulnerability identified as CVE-2016-8819 represents a critical security flaw within NVIDIA's Windows GPU display drivers that affects all versions of the software. This issue resides within the kernel mode layer of the graphics driver, specifically within the nvlddmkm.sys component which serves as the kernel-mode driver for NVIDIA's display adapters. The vulnerability manifests in the DxgkDdiEscape handler, which is responsible for processing escape commands that allow user-mode applications to communicate with the kernel-mode driver. This particular handler presents a dangerous condition where it may inadvertently return a handle to a kernel object to user-mode processes, creating a fundamental security breach in the driver's privilege separation mechanisms.
The technical flaw stems from improper validation and handling of kernel object handles within the DxgkDdiEscape function, which operates under the Windows Display Driver Model (WDDM) framework. When user-mode applications submit escape commands to the graphics driver, the kernel-mode handler should strictly validate the operations and ensure that no direct access to kernel objects is granted to unprivileged users. However, the vulnerability allows for a scenario where a kernel object handle might be leaked to user-mode, effectively providing unauthorized access to kernel-level resources. This flaw directly violates the fundamental security principle of privilege separation and can be exploited through carefully crafted escape commands that manipulate the driver's object handle management system. The vulnerability falls under CWE-264, which specifically addresses permissions, privileges, and access control issues in software systems.
The operational impact of this vulnerability is severe and multifaceted, potentially enabling both privilege escalation and denial of service attacks against affected systems. An attacker with local user access could exploit this vulnerability to escalate their privileges from standard user level to kernel-level execution, effectively gaining complete control over the system. This privilege escalation capability arises because the leaked kernel object handle provides access to critical kernel resources that should only be accessible to the operating system kernel itself. Additionally, the vulnerability can be leveraged for denial of service attacks by manipulating kernel objects in ways that cause system instability or complete system crashes. The attack surface is particularly concerning as it affects all versions of NVIDIA Windows GPU drivers, meaning that a wide range of systems could be vulnerable simultaneously. This vulnerability aligns with ATT&CK technique T1068, which covers 'Exploitation for Privilege Escalation' and represents a classic kernel-mode exploit that can be used to bypass operating system security controls.
Mitigation strategies for CVE-2016-8819 require immediate action from system administrators and security teams to address the vulnerability through official driver updates from NVIDIA. The most effective solution involves installing the latest NVIDIA GPU display drivers that contain patches specifically designed to address the object handle leakage issue in the DxgkDdiEscape handler. System administrators should prioritize patching affected systems, particularly those running on enterprise networks where the risk of exploitation is higher. Additional mitigations include implementing security measures such as disabling unnecessary graphics driver functionality, monitoring for suspicious escape command usage, and maintaining strict access controls on systems with NVIDIA graphics adapters. Organizations should also consider implementing runtime protection mechanisms and behavioral monitoring to detect potential exploitation attempts. The vulnerability demonstrates the critical importance of proper kernel-mode driver security practices and highlights the need for comprehensive code review processes to prevent similar issues in graphics driver implementations. Security teams should also consider implementing network segmentation and access control measures to limit the potential impact of successful exploitation attempts, as the vulnerability could be leveraged to establish persistent access to compromised systems.