CVE-2021-1091 in GPU Display Driver
Summary
by MITRE • 07/22/2021
NVIDIA GPU Display driver for Windows contains a vulnerability where an unprivileged user can create a file hard link that causes the driver to overwrite a file that requires elevated privilege to modify, which could lead to data loss or denial of service.
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Analysis
by VulDB Data Team • 07/27/2021
The vulnerability identified as CVE-2021-1091 resides within the NVIDIA GPU Display driver for Windows operating system, representing a significant privilege escalation risk that affects users running affected driver versions. This flaw stems from inadequate access control mechanisms within the driver's file handling processes, creating an exploitable condition where standard user accounts can manipulate system files through symbolic link manipulation. The vulnerability specifically targets the driver's inability to properly validate file access permissions when processing hard link creation requests, allowing unauthorized users to potentially overwrite protected system files with elevated privileges.
The technical implementation of this vulnerability involves the exploitation of a race condition or improper privilege checking mechanism within the Windows display driver framework. When an unprivileged user creates a hard link to a target file, the driver processes this request without sufficient validation of the requesting user's permissions or the target file's security attributes. This weakness manifests in the driver's file system interaction layer where it fails to properly enforce access control policies, particularly when dealing with files that are normally restricted to administrator or system-level access. The flaw essentially allows a user to bypass normal Windows file permission controls through the driver's handling of file link operations.
From an operational impact perspective, this vulnerability presents multiple attack vectors that could result in significant system compromise. An attacker with local user access could potentially overwrite critical system files, configuration data, or even driver components, leading to system instability, denial of service conditions, or complete system compromise. The potential for data loss exists when critical files are overwritten with malicious content or corrupted data, while the possibility of denial of service means that legitimate system operations could be disrupted through the corruption of essential driver or system files. This vulnerability particularly affects enterprise environments where multiple users share systems, as it could enable privilege escalation attacks that bypass normal security controls.
The security implications extend beyond immediate exploitation to encompass broader system integrity concerns, as this vulnerability could serve as a foundation for more sophisticated attacks. Attackers could leverage this flaw to establish persistent access by modifying system files, potentially creating backdoors or disabling security features. The vulnerability's classification aligns with CWE-264, which addresses permissions, privileges, and access controls, and could be mapped to ATT&CK technique T1068, which covers local privilege escalation through system binary modification. Organizations should consider this vulnerability in their threat modeling exercises and assess the potential for lateral movement or persistence through the manipulation of system files that require elevated privileges to modify.
Mitigation strategies for CVE-2021-1091 should include immediate driver updates from NVIDIA to address the specific privilege escalation flaw, along with enhanced monitoring of file system access patterns for unusual hard link creation activities. System administrators should implement strict access controls and file integrity monitoring solutions to detect unauthorized modifications to critical system files. Additionally, organizations should consider implementing least privilege principles and user access controls to minimize the potential impact of such vulnerabilities. The remediation process should involve comprehensive testing of updated drivers in controlled environments before deployment to production systems, ensuring that the patch does not introduce compatibility issues with existing applications or system configurations.