CVE-2018-6247 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 NULL pointer dereference may lead to denial of service or possible escalation of privileges.
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Analysis
by VulDB Data Team • 01/20/2020
The vulnerability identified as CVE-2018-6247 resides within the NVIDIA Windows GPU Display Driver component, specifically within the kernel mode layer known as nvlddmkm.sys. This flaw manifests in the DxgkDdiEscape handler which serves as an interface for graphics driver operations. The issue stems from inadequate input validation and error handling mechanisms within the kernel mode driver code, creating a scenario where a maliciously crafted escape command can trigger a NULL pointer dereference condition. Such vulnerabilities are particularly dangerous as they operate within the privileged kernel space context, potentially allowing attackers to exploit the weakness for unauthorized system access or service disruption.
The technical implementation of this vulnerability involves the DxgkDdiEscape function which processes escape commands from user-mode applications to communicate with the graphics kernel driver. When processing certain malformed escape parameters, the driver fails to properly validate pointer references before dereferencing them, leading to a NULL pointer exception that crashes the graphics driver service. This specific flaw falls under the CWE-476 category of NULL Pointer Dereference, a common vulnerability pattern that occurs when software attempts to access a memory location pointed to by a NULL reference. The vulnerability's impact is amplified by its location within the kernel mode driver, where the privilege level allows for potential privilege escalation attacks.
The operational consequences of CVE-2018-6247 extend beyond simple denial of service conditions to encompass potential privilege escalation scenarios that could allow attackers to gain elevated system privileges. When the kernel mode driver crashes due to the NULL pointer dereference, the system experiences a denial of service condition that disrupts graphics functionality and potentially affects overall system stability. However, the more concerning aspect involves the possibility of privilege escalation, where an attacker with user-level access could potentially leverage this vulnerability to execute arbitrary code with kernel-level privileges. This aligns with ATT&CK technique T1068 which focuses on 'Local Privilege Escalation' through kernel exploits, making this vulnerability particularly attractive to threat actors seeking persistent system access.
Mitigation strategies for CVE-2018-6247 should prioritize immediate driver updates from NVIDIA, as the vendor has released patches addressing this specific vulnerability. Organizations should implement comprehensive patch management protocols to ensure all affected systems receive the necessary updates without delay. Additionally, system administrators should consider implementing application whitelisting controls to restrict the execution of potentially malicious escape commands that could trigger the vulnerability. Network segmentation and privilege separation measures can further reduce the attack surface by limiting user access to graphics driver interfaces. The vulnerability demonstrates the critical importance of kernel mode security validation and proper error handling, reinforcing industry best practices outlined in standards such as the CERT/CC Secure Coding Standards and NIST SP 800-144 guidelines for kernel-level security controls. Regular security assessments and vulnerability scanning should include checks for outdated graphics drivers to prevent exploitation of similar kernel mode vulnerabilities that may exist in other system components.