CVE-2021-1075: Nvidia GPU Display Driver Escalation Flaw

CVE-2021-1075 Overview

NVIDIA Windows GPU Display Driver for Windows contains a vulnerability in the kernel mode layer (nvlddmkm.sys) handler for DxgkDdiEscape where the program dereferences a pointer that contains a location for memory that is no longer valid. This use-after-free condition may lead to code execution, denial of service, or escalation of privileges. While the attacker does not have control over the information being accessed, they may conduct limited data modification.

Critical Impact

Local attackers with low privileges can exploit this kernel-level vulnerability to potentially execute arbitrary code, cause system crashes, or escalate privileges on Windows systems running affected NVIDIA GPU drivers.

Affected Products

• NVIDIA GPU Display Driver for Windows (all versions prior to the security patch)
• Systems using NVIDIA graphics cards with vulnerable nvlddmkm.sys kernel driver
• Windows workstations and servers with NVIDIA GPU hardware

Discovery Timeline

• 2021-04-21 - CVE-2021-1075 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2021-1075

Vulnerability Analysis

This vulnerability represents a use-after-free condition (CWE-476) in the NVIDIA Windows GPU Display Driver's kernel mode layer. The vulnerable component is nvlddmkm.sys, specifically within the DxgkDdiEscape handler. This function is a DirectX Graphics Kernel Subsystem callback that allows user-mode applications to communicate with the kernel-mode driver through escape calls.

The vulnerability occurs when the driver dereferences a pointer that references memory that has already been freed or is no longer valid. This type of memory corruption vulnerability in kernel-mode drivers is particularly dangerous because kernel-mode code runs with the highest privileges on Windows systems. Successful exploitation could allow an attacker to execute arbitrary code in kernel context, potentially leading to complete system compromise.

The local attack vector requires an attacker to have existing access to the target system with low-level privileges. The vulnerability affects the change in scope boundary, meaning successful exploitation can impact resources beyond the vulnerable component itself—specifically the system's integrity and availability.

Root Cause

The root cause of this vulnerability is improper memory management in the DxgkDdiEscape handler within the nvlddmkm.sys kernel driver. The code fails to properly validate that a memory pointer is still valid before dereferencing it, leading to a use-after-free condition. This occurs when memory is freed but the pointer to that memory is not properly nullified or checked before subsequent use.

Attack Vector

The attack vector for CVE-2021-1075 is local, requiring the attacker to have existing access to the target Windows system. The exploitation path involves:

1. A local attacker with low-level privileges crafts a malicious application or leverages an existing process
2. The attacker sends specially crafted escape calls to the NVIDIA driver through the DxgkDdiEscape interface
3. These calls trigger the use-after-free condition in the kernel driver
4. Upon successful exploitation, the attacker may achieve code execution in kernel mode, cause a system crash (blue screen of death), or escalate privileges

The vulnerability can be exploited without user interaction, making it particularly concerning for multi-user environments where unprivileged users may attempt to escalate their access.

Detection Methods for CVE-2021-1075

Indicators of Compromise

• Unexpected system crashes (BSOD) with references to nvlddmkm.sys in crash dumps
• Unusual processes making excessive or abnormal IOCTL calls to NVIDIA driver interfaces
• Anomalous memory access patterns in kernel space related to display driver operations
• Privilege escalation events following suspicious GPU driver interactions

Detection Strategies

• Monitor for crash dumps that reference nvlddmkm.sys as the faulting driver
• Implement kernel-level monitoring for suspicious escape calls to DirectX Graphics Kernel Subsystem
• Deploy endpoint detection solutions capable of identifying use-after-free exploitation attempts
• Audit driver versions across the environment to identify unpatched NVIDIA installations

Monitoring Recommendations

• Enable Windows crash dump collection and analyze for patterns indicating exploitation attempts
• Configure SIEM rules to correlate NVIDIA driver-related events with privilege escalation indicators
• Monitor for unauthorized modifications to display driver files or registry settings
• Implement file integrity monitoring for nvlddmkm.sys and related NVIDIA driver components

How to Mitigate CVE-2021-1075

Immediate Actions Required

• Update NVIDIA GPU Display Drivers to the latest patched version immediately
• Review the NVIDIA Security Advisory for specific version requirements
• Inventory all systems with NVIDIA GPUs to ensure comprehensive patching
• Restrict local access to systems until patches can be applied in high-security environments

Patch Information

NVIDIA has released security updates to address this vulnerability. Administrators should consult the official NVIDIA Support Article for specific version numbers and download links for patched drivers. The security bulletin provides detailed information about affected driver branches and the corresponding fixed versions.

To update drivers:

1. Download the latest driver from NVIDIA's official website or enterprise deployment tools
2. Uninstall the current vulnerable driver version
3. Install the patched driver and reboot the system
4. Verify the installation by checking the driver version in Device Manager

Workarounds

• Limit local access to systems with NVIDIA GPUs to trusted users only
• Implement application whitelisting to prevent untrusted applications from interacting with GPU drivers
• Consider using virtualization-based security features where available to isolate kernel components
• Monitor and alert on any attempts to exploit DirectX Graphics Kernel interfaces

# Verify NVIDIA driver version on Windows (PowerShell)
Get-WmiObject Win32_PnPSignedDriver | Where-Object { $_.DeviceName -like "*NVIDIA*" } | Select-Object DeviceName, DriverVersion