CVE-2019-7240 in System Monitor
Summary
by MITRE
An issue was discovered in WinRing0x64.sys in Moo0 System Monitor 1.83. The vulnerable driver exposes a wrmsr instruction via IOCTL 0x9C402088 and does not properly filter the Model Specific Register (MSR). Allowing arbitrary MSR writes can lead to Ring-0 code execution and escalation of privileges.
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Analysis
by VulDB Data Team • 05/11/2024
The vulnerability identified as CVE-2019-7240 resides within the WinRing0x64.sys driver component of Moo0 System Monitor version 1.83, representing a critical privilege escalation flaw that directly impacts system security integrity. This issue manifests through an improperly configured IOCTL (Input/Output Control) interface that exposes the wrmsr instruction, which is fundamental to low-level hardware manipulation within Windows operating systems. The driver's failure to adequately validate or filter Model Specific Register (MSR) access creates a dangerous pathway for malicious actors to execute arbitrary code at the most privileged ring level, effectively bypassing standard operating system security mechanisms.
The technical implementation of this vulnerability stems from the driver's exposure of IOCTL 0x9C402088, which serves as an interface for executing the wrmsr instruction that writes to Model Specific Registers. These registers contain critical processor control information and configuration data that should normally be restricted to kernel-level operations. When the driver fails to properly validate the MSR address and data values passed through this interface, it allows any user-mode process to write to any MSR location, including those that control processor features, performance monitoring, and security-related functions. This lack of input validation creates a direct pathway for privilege escalation, as malicious code can manipulate processor state to gain ring-0 execution privileges, effectively elevating user-level processes to kernel-level access.
The operational impact of CVE-2019-7240 extends beyond simple privilege escalation, as it provides attackers with unprecedented control over system hardware and core operating system functions. The ability to write arbitrary values to MSRs enables attackers to manipulate processor security features, disable security mechanisms, modify system behavior, and potentially establish persistent backdoors. This vulnerability directly maps to attack techniques described in the MITRE ATT&CK framework under privilege escalation tactics, specifically targeting the use of kernel exploits and system modification techniques. The vulnerability represents a classic example of a driver-level security flaw that can be exploited without requiring physical access or advanced exploitation skills, making it particularly dangerous in enterprise environments.
From a compliance and security standards perspective, this vulnerability directly relates to CWE-119, which addresses "Improper Access Control" and CWE-787, which covers "Out-of-bounds Write" in kernel-mode drivers. The flaw demonstrates inadequate input validation and privilege enforcement mechanisms that violate fundamental security principles outlined in various cybersecurity frameworks including NIST SP 800-144 and ISO 27001. Organizations should consider implementing immediate mitigations including driver signature enforcement, disabling unnecessary kernel interfaces, and deploying endpoint protection solutions that monitor for suspicious driver behavior. The vulnerability also highlights the importance of proper software supply chain security, as this issue was present in a widely distributed system monitoring tool, emphasizing the need for regular security assessments of third-party software components and their kernel-mode drivers.