CVE-2021-34403 in Shield TV
Summary
by MITRE • 01/18/2022
NVIDIA Linux distributions contain a vulnerability in nvmap ioctl, which allows any user with a local account to exploit a use-after-free condition, leading to code privilege escalation, loss of confidentiality and integrity, or denial of service.
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Analysis
by VulDB Data Team • 01/20/2022
The vulnerability identified as CVE-2021-34403 resides within NVIDIA's Linux driver distributions and specifically targets the nvmap ioctl implementation. This flaw represents a critical security weakness that fundamentally undermines system integrity by creating an exploitable use-after-free condition. The nvmap subsystem serves as a memory management interface for NVIDIA graphics drivers, facilitating communication between user-space applications and kernel-space driver components. When a user account gains access to execute malicious code against this interface, the vulnerability becomes exploitable through local privilege escalation techniques.
The technical nature of this vulnerability stems from improper memory management within the nvmap ioctl handler, where freed memory regions are accessed after being deallocated. This use-after-free condition occurs when the kernel driver fails to properly validate input parameters or maintain proper reference counting during memory operations. The flaw allows an unprivileged local user to manipulate ioctl commands in such a way that they can cause the kernel to access memory that has already been freed, potentially leading to arbitrary code execution with kernel privileges. This type of vulnerability falls under the CWE-416 category of use-after-free conditions, which are particularly dangerous in kernel contexts where they can lead to complete system compromise.
The operational impact of CVE-2021-34403 extends beyond simple privilege escalation, creating multiple vectors for system compromise. An attacker exploiting this vulnerability can gain root-level access to affected systems, potentially leading to complete loss of confidentiality and integrity across the entire platform. The vulnerability affects all NVIDIA Linux distributions that implement the nvmap interface, making it particularly concerning for enterprise environments where graphics processing units are commonly utilized. Additionally, the denial of service aspect means that even unsuccessful exploitation attempts could destabilize system operations, potentially causing service interruptions that impact business continuity. The vulnerability's exploitation requires only local user access, making it particularly dangerous as it can be leveraged by users who do not possess elevated privileges initially.
Mitigation strategies for this vulnerability require immediate attention from system administrators and security teams. The most effective approach involves applying the latest NVIDIA driver updates that contain patches addressing the specific use-after-free condition in the nvmap ioctl implementation. Organizations should prioritize patch deployment across all affected systems, particularly those running NVIDIA graphics hardware in production environments. Additional defensive measures include implementing proper access controls to limit local user privileges, monitoring for suspicious ioctl activity, and maintaining up-to-date system hardening practices. Security teams should also consider implementing kernel module integrity checks and monitoring for unauthorized driver modifications. The vulnerability's classification aligns with ATT&CK technique T1068 which covers privilege escalation through local exploits, making it essential for security operations centers to monitor for indicators of compromise related to this specific attack vector. System administrators must also consider the broader implications of this vulnerability within their security posture, as it represents a critical weakness that could be leveraged by adversaries to establish persistent access to compromised systems.