CVE-2017-6256 in Windows GPU Display Driver
Summary
by MITRE
NVIDIA Windows GPU Display Driver contains a vulnerability in the kernel mode layer (nvlddmkm.sys) handler for DxgkDdiEscape where a value passed from a user to the driver is not correctly validated and used as the index to an array which may lead to denial of service or potential escalation of privileges.
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Analysis
by VulDB Data Team • 11/02/2019
The vulnerability identified as CVE-2017-6256 resides within the NVIDIA Windows GPU Display Driver component, specifically within the kernel mode layer represented by the nvlddmkm.sys module. This flaw manifests in the DxgkDdiEscape handler function which processes escape commands from user-mode applications to communicate with the graphics kernel. The issue stems from inadequate validation of user-supplied data that is subsequently used as an array index, creating a potential pathway for exploitation that could compromise system integrity and stability. The vulnerability affects Windows operating systems that utilize NVIDIA graphics drivers, making it a significant concern for enterprise environments where graphics processing is heavily utilized.
The technical implementation of this vulnerability follows a classic buffer overflow pattern where user-provided input lacks proper bounds checking before being used as an array indexing mechanism. When a malicious application invokes the DxgkDdiEscape function with crafted parameters, the driver processes these inputs without sufficient validation, allowing an attacker to potentially manipulate the array access pattern. This flaw operates at the kernel level within the display driver model, where the graphics kernel manages hardware resources and system graphics operations. The improper validation creates a condition where an attacker could cause the driver to access memory locations outside the intended array boundaries, potentially leading to memory corruption or arbitrary code execution.
The operational impact of CVE-2017-6256 extends beyond simple denial of service scenarios, as it presents potential privilege escalation opportunities that could allow attackers to elevate their access level from standard user to system administrator. This vulnerability falls under the CWE-129 weakness category, specifically addressing improper validation of array indices, which is a fundamental security principle that should be enforced at all levels of software development. The attack surface is particularly concerning given that graphics drivers operate with high privileges and have direct access to hardware resources, making successful exploitation potentially devastating. The vulnerability could be leveraged by attackers to execute malicious code with kernel-level privileges, effectively bypassing standard operating system security mechanisms and potentially compromising the entire system.
Mitigation strategies for this vulnerability should focus on immediate driver updates from NVIDIA, which would include patches addressing the array validation flaw in the DxgkDdiEscape handler. System administrators should prioritize applying these updates across all affected systems, particularly those running in enterprise environments where graphics processing is critical. Additional defensive measures include implementing application whitelisting policies to restrict which applications can interact with graphics kernel functions, monitoring for suspicious escape command patterns, and employing kernel-mode exploit detection mechanisms. The vulnerability also highlights the importance of following secure coding practices, specifically those related to input validation and memory safety, which aligns with ATT&CK technique T1068 for local privilege escalation and T1059 for command and scripting interpreter execution. Organizations should also consider implementing network segmentation to limit the potential impact of successful exploitation and maintain comprehensive system monitoring to detect anomalous graphics driver behavior.