CVE-2016-8817 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 DxgDdiEscape where a value passed from a user to the driver is used without validation as the size input to memcpy(), causing a buffer overflow, leading to denial of service or potential escalation of privileges.
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Analysis
by VulDB Data Team • 07/09/2019
The vulnerability identified as CVE-2016-8817 represents a critical buffer overflow flaw within NVIDIA's Windows GPU display drivers that affects all versions of the software. This issue resides in the kernel mode layer component known as nvlddmkm.sys, which serves as the core driver interface between the operating system and graphics hardware. The vulnerability specifically manifests in the DxgDdiEscape handler, a function designed to process escape sequences for DirectX graphics operations. When user-mode applications submit data to this handler, the driver fails to properly validate the size parameter before utilizing it in a memcpy() operation, creating a scenario where arbitrary memory corruption can occur.
The technical exploitation of this vulnerability stems from insufficient input validation mechanisms within the kernel-mode driver code. The DxgDdiEscape handler receives user-supplied data that includes a size parameter, which should be validated against acceptable bounds before being used in memory operations. However, the driver directly employs this unvalidated parameter as the size argument for memcpy(), bypassing any boundary checks or sanitization procedures. This design flaw allows an attacker to craft malicious input that exceeds the intended buffer limits, resulting in memory corruption that can overwrite adjacent memory locations. The vulnerability classifies under CWE-121, which describes stack-based buffer overflow conditions, though the actual implementation involves heap memory corruption due to kernel-mode execution context.
The operational impact of CVE-2016-8817 extends beyond simple denial of service scenarios to potentially enable privilege escalation attacks. When exploited successfully, the buffer overflow can lead to arbitrary code execution within the kernel context, allowing attackers to gain elevated privileges and potentially compromise the entire system. The kernel-mode nature of the vulnerability means that successful exploitation could result in complete system compromise, as the attacker would gain access to the most privileged execution environment. Additionally, the vulnerability can cause system instability and denial of service conditions, making the affected systems unreliable and potentially unusable. The attack surface is particularly concerning given that GPU drivers are essential components of modern operating systems, making exploitation relatively straightforward for determined attackers.
Mitigation strategies for CVE-2016-8817 should focus on both immediate remediation and long-term security hardening measures. The most effective immediate solution involves updating to the latest NVIDIA GPU display drivers, which contain patches addressing the validation flaw in the DxgDdiEscape handler. System administrators should also implement additional security controls such as kernel-mode driver signature enforcement, which can prevent unauthorized or unpatched drivers from loading into the system. The vulnerability demonstrates the importance of input validation in kernel-mode code, aligning with ATT&CK technique T1068 which covers privilege escalation through kernel exploits. Organizations should also consider implementing runtime application control measures and monitoring for suspicious kernel-mode activities that could indicate exploitation attempts. Regular security assessments and vulnerability scanning should include checks for outdated GPU drivers, as this vulnerability represents a persistent risk in unpatched systems.