CVE-2016-8820 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 check on a function return value is missing, potentially allowing an uninitialized value to be used as the source of a strcpy() call, leading to denial of service or information disclosure.
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Analysis
by VulDB Data Team • 07/09/2019
The vulnerability identified as CVE-2016-8820 resides within NVIDIA's Windows GPU Display Driver kernel mode component known as nvlddmkm.sys. This flaw specifically affects the DxgDdiEscape handler functionality which serves as a critical interface between the display driver and the Windows graphics subsystem. The vulnerability manifests in the kernel mode layer where proper input validation and error handling mechanisms are absent, creating a dangerous condition that can be exploited by malicious actors. The affected driver versions span across all releases of NVIDIA's Windows GPU drivers, making this a widespread issue affecting numerous systems running NVIDIA graphics hardware.
The technical flaw occurs when the DxgDdiEscape handler processes certain escape codes without adequately validating the return value of a preceding function call. This missing validation check allows an uninitialized memory value to be passed directly into a strcpy() function call, which represents a classic buffer overflow vulnerability pattern. The absence of proper error checking creates a condition where the source parameter for the string copy operation contains unpredictable data, potentially leading to memory corruption or exploitation. This vulnerability directly maps to CWE-248, which describes an unspecified return value that is used without proper validation, and also aligns with CWE-125, representing an out-of-bounds read condition that can occur when uninitialized values are used in operations.
The operational impact of CVE-2016-8820 extends beyond simple denial of service conditions to potentially enable information disclosure attacks. When an uninitialized value is used in a strcpy() operation, the system may inadvertently expose sensitive memory contents to unauthorized processes or malicious code. The denial of service component occurs when the corrupted memory state causes the graphics driver to crash or become unresponsive, resulting in system instability and potential complete system hangs. Attackers could leverage this vulnerability to cause persistent system disruptions or to gather information about system memory layout for more sophisticated attacks. The kernel mode nature of the vulnerability means that successful exploitation could potentially allow privilege escalation or complete system compromise.
Mitigation strategies for CVE-2016-8820 should prioritize immediate driver updates from NVIDIA, as the vendor has released patches addressing this specific vulnerability. System administrators should implement comprehensive patch management protocols to ensure all affected NVIDIA GPU drivers are updated across enterprise environments. Additional protective measures include implementing kernel mode protection features such as Windows Driver Verifier, enabling exploit protection mechanisms, and monitoring for unusual graphics driver behavior or system crashes. The vulnerability demonstrates the importance of proper error handling in kernel mode components and highlights the need for adherence to secure coding practices as outlined in the CERT Secure Coding Standards. Organizations should also consider implementing network segmentation and access controls to limit potential exploitation vectors, particularly in environments where graphics drivers are exposed to untrusted users or applications. This vulnerability serves as a reminder of the critical security implications inherent in kernel mode driver code and the necessity for rigorous security testing and validation of all system components that operate with elevated privileges.