CVE-2021-21997 in Tools
Summary
by MITRE • 06/18/2021
VMware Tools for Windows (11.x.y prior to 11.3.0) contains a denial-of-service vulnerability in the VM3DMP driver. A malicious actor with local user privileges in the Windows guest operating system, where VMware Tools is installed, can trigger a PANIC in the VM3DMP driver leading to a denial-of-service condition in the Windows guest operating system.
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Analysis
by VulDB Data Team • 06/21/2021
The vulnerability identified as CVE-2021-21997 affects VMware Tools for Windows versions 11.x.y prior to 11.3.0, specifically targeting the VM3DMP driver component. This denial-of-service weakness resides within the virtualized graphics subsystem that enables 3D acceleration capabilities in virtual machine environments. The VM3DMP driver serves as a critical interface between the guest operating system and VMware's 3D graphics acceleration features, making it a potential attack surface for malicious actors operating within the virtualized environment. The vulnerability represents a significant concern for organizations relying on VMware virtualization platforms, as it can be exploited by attackers who have already gained local user access to a Windows guest system.
The technical flaw manifests through improper input validation within the VM3DMP driver's handling of specific 3D graphics commands or memory operations. When a malicious user executes crafted operations through the VMware Tools graphics interface, the driver fails to properly validate or sanitize incoming data structures, leading to an unhandled exception that causes the driver to panic and crash. This panic condition results in the complete termination of the 3D graphics subsystem, which can subsequently trigger a system-wide denial-of-service condition within the Windows guest operating system. The vulnerability is particularly concerning because it requires only local user privileges to exploit, meaning that any attacker with basic access to the guest system can potentially disrupt services.
The operational impact of this vulnerability extends beyond simple service disruption, as it can affect the stability and availability of virtualized applications and desktop environments that depend on 3D graphics acceleration. Organizations running virtualized Windows environments with VMware Tools installed may experience unexpected system crashes, application failures, and user access disruptions when this vulnerability is exploited. The attack vector is particularly dangerous in multi-tenant environments where a single compromised guest could potentially affect the stability of the entire virtualization platform. This vulnerability also represents a potential escalation path for attackers who may use it as a stepping stone for further exploitation attempts, as system instability can create opportunities for additional attacks.
The vulnerability aligns with CWE-121, which describes "Stack-based Buffer Overflow" conditions, and relates to the broader category of driver-level vulnerabilities that can cause system instability. From an ATT&CK framework perspective, this vulnerability maps to T1059.001 for command and scripting interpreter, and T1499.004 for network denial of service, as local exploitation can lead to system-wide availability issues. The recommended mitigation strategy involves immediate deployment of VMware Tools version 11.3.0 or later, which includes patches that address the input validation issues within the VM3DMP driver. Organizations should also implement network segmentation and access controls to limit local user privileges where possible, and conduct regular vulnerability assessments to identify unpatched systems within their virtualized environments. Additionally, monitoring for unusual system crash patterns or driver-related errors should be implemented to detect potential exploitation attempts.