CVE-2018-6963 in Workstation
Summary
by MITRE
VMware Workstation (14.x before 14.1.2) and Fusion (10.x before 10.1.2) contain multiple denial-of-service vulnerabilities that occur due to NULL pointer dereference issues in the RPC handler. Successful exploitation of these issues may allow an attacker with limited privileges on the guest machine trigger a denial-of-Service of their guest machine.
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Analysis
by VulDB Data Team • 03/14/2023
The vulnerability identified as CVE-2018-6963 affects VMware Workstation version 14.x before 14.1.2 and VMware Fusion version 10.x before 10.1.2, representing critical flaws in the virtualization platforms' remote procedure call handling mechanisms. These vulnerabilities stem from improper input validation within the RPC handler components that process guest machine communications, creating exploitable conditions that can be leveraged by malicious actors. The specific nature of the flaw involves NULL pointer dereference conditions that occur when the system attempts to process malformed or unexpected RPC requests from guest operating systems. This type of vulnerability falls under CWE-476 which specifically addresses NULL pointer dereference issues, making it a well-documented and dangerous class of software defect that can lead to system instability.
The technical implementation of these vulnerabilities occurs within the RPC handler subsystem where the software fails to properly validate incoming requests before attempting to dereference pointers that may be NULL. When a guest machine sends specially crafted RPC messages that contain malformed data structures or unexpected parameter values, the handler code attempts to access memory locations that have not been properly initialized or allocated. This leads to immediate system crashes or hangs that effectively deny service to legitimate users of the virtual machine. The vulnerability is particularly concerning because it requires only limited privileges within the guest operating system to exploit, meaning that any user with access to run applications inside the virtual machine can potentially trigger the denial-of-service condition. This makes the vulnerability accessible to a broad range of threat actors including malicious insiders and compromised guest systems.
From an operational perspective, the impact of CVE-2018-6963 represents a significant risk to virtualized environments where multiple users share the same host system. The denial-of-service conditions can affect not only the targeted virtual machine but may also impact overall system stability and performance, particularly in environments where multiple virtual machines are running simultaneously. Attackers can exploit this vulnerability to disrupt business operations, cause service interruptions, or potentially create conditions that allow for further exploitation. The vulnerability's classification under the ATT&CK framework would likely fall under the T1499 category for Network Denial of Service, as it enables attackers to consume system resources and render virtual machines unavailable. Additionally, the weakness creates opportunities for attackers to escalate their privileges or use the denial-of-service as a stepping stone for more sophisticated attacks targeting the host system or other virtual machines running on the same infrastructure.
The primary mitigation strategy for CVE-2018-6963 involves applying the official patches released by VMware, specifically upgrading to VMware Workstation 14.1.2 or later versions and VMware Fusion 10.1.2 or later. Organizations should also implement network segmentation and access controls to limit guest machine privileges and reduce the attack surface available to potential exploiters. Regular monitoring of virtual machine logs for unusual RPC activity and implementing intrusion detection systems can help identify exploitation attempts before they succeed. System administrators should also consider implementing virtual machine isolation techniques and ensuring that guest operating systems are regularly updated with security patches to prevent exploitation through additional attack vectors. The vulnerability demonstrates the importance of proper input validation and error handling in system components that process untrusted data from guest environments, reinforcing industry best practices for secure coding and robust system design.