CVE-2017-4945 in Workstation
Summary
by MITRE
VMware Workstation (14.x and 12.x) and Fusion (10.x and 8.x) contain a guest access control vulnerability. This issue may allow program execution via Unity on locked Windows VMs. VMware Tools must be updated to 10.2.0 for each VM to resolve CVE-2017-4945. VMware Tools 10.2.0 is consumed by Workstation 14.1.0 and Fusion 10.1.0 by default.
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Analysis
by VulDB Data Team • 01/28/2021
This vulnerability resides within VMware's virtualization platforms affecting Workstation versions 12.x and 14.x, as well as Fusion versions 8.x and 10.x, representing a critical guest access control flaw that undermines the fundamental security isolation between host and guest operating systems. The issue specifically manifests when Unity mode is enabled on Windows virtual machines, creating an unintended execution path that allows malicious code to run on locked Windows VMs. This vulnerability falls under CWE-284, which addresses improper access control mechanisms, and aligns with ATT&CK technique T1059.001 for command and script interpreter execution, as it enables unauthorized program execution within the virtualized environment. The flaw exploits the insufficient privilege separation between the host system and the guest operating system, particularly when VMware Tools components are not properly updated.
The technical implementation of this vulnerability stems from inadequate access control checks within VMware's Unity mode implementation, which is designed to seamlessly integrate guest applications with the host desktop environment. When a Windows VM is locked while Unity mode is active, the system fails to properly enforce security boundaries that should prevent guest processes from executing code with elevated privileges. This creates a scenario where malicious actors can leverage the Unity interface to bypass normal authentication mechanisms and execute arbitrary code on the locked virtual machine. The vulnerability specifically affects the interaction between VMware Tools and the Windows kernel, where insufficient validation occurs during the guest-to-host communication process. This flaw represents a significant compromise of the hypervisor's security model, as it allows for privilege escalation without requiring direct access to the host system.
The operational impact of this vulnerability extends beyond simple unauthorized code execution, potentially enabling attackers to escalate privileges, access sensitive data, or establish persistent access within the virtualized environment. When combined with other vulnerabilities or attack vectors, this flaw could allow for complete compromise of the virtual machine and potentially the host system itself. The vulnerability affects organizations that rely heavily on virtualization for desktop and application virtualization, particularly those using VMware's Unity mode for enhanced user experience. Attackers could exploit this vulnerability to gain unauthorized access to locked virtual machines, potentially accessing confidential information or using the compromised VM as a pivot point for further attacks within the network infrastructure. The vulnerability is particularly concerning in enterprise environments where multiple users share virtual desktop infrastructure and where VMs may be left locked during non-business hours.
Mitigation strategies for this vulnerability require immediate updates to VMware Tools components to version 10.2.0 or later, which addresses the access control flaw through enhanced privilege validation mechanisms. Organizations must ensure that all affected virtual machines have VMware Tools updated to the patched version, as the vulnerability affects multiple versions of VMware Workstation and Fusion platforms. The recommended remediation approach involves updating VMware Tools on each affected VM individually, as the patch must be applied at the guest operating system level rather than through host-level configuration changes. Additionally, administrators should consider disabling Unity mode on virtual machines that handle sensitive data or operate in high-security environments until the vulnerability is fully addressed. The patch implementation should be part of a broader security update strategy that includes regular assessment of virtualization platform security, monitoring for similar access control vulnerabilities, and maintaining updated security baselines for all virtualized environments. This vulnerability demonstrates the critical importance of keeping virtualization components updated and highlights the need for comprehensive security testing of virtualization platforms to prevent similar access control issues.