CVE-2017-4904 in ESXi
Summary
by MITRE
The XHCI controller in VMware ESXi 6.5 without patch ESXi650-201703410-SG, 6.0 U3 without patch ESXi600-201703401-SG, 6.0 U2 without patch ESXi600-201703403-SG, 6.0 U1 without patch ESXi600-201703402-SG, and 5.5 without patch ESXi550-201703401-SG; Workstation Pro / Player 12.x prior to 12.5.5; and Fusion Pro / Fusion 8.x prior to 8.5.6 has uninitialized memory usage. This issue may allow a guest to execute code on the host. The issue is reduced to a Denial of Service of the guest on ESXi 5.5.
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Analysis
by VulDB Data Team • 12/26/2020
The vulnerability described in CVE-2017-4904 represents a critical uninitialized memory access flaw within the USB eXtensible Host Controller Interface (XHCI) implementation of VMware virtualization products. This vulnerability affects multiple versions of VMware ESXi, Workstation Pro/Player, and Fusion Pro/Fusion, specifically targeting the handling of USB device communications within virtualized environments. The issue stems from improper initialization of memory regions used during USB controller operations, creating potential pathways for malicious code execution. The vulnerability is categorized under CWE-457 as "Use of Uninitialized Variable," which directly relates to the improper handling of memory that has not been properly initialized before use.
The technical flaw manifests when a guest operating system running within a VMware virtual machine attempts to communicate with USB devices through the XHCI controller. During this process, the controller fails to properly initialize certain memory regions before utilizing them, potentially allowing an attacker to manipulate uninitialized memory locations. This memory corruption can be exploited to execute arbitrary code with host-level privileges, effectively bypassing the isolation typically maintained between guest and host systems. The vulnerability's impact varies across different VMware products and versions, with ESXi 5.5 being limited to denial of service conditions while newer versions present full code execution capabilities.
The operational implications of this vulnerability are severe for organizations relying on VMware virtualization environments. Attackers with access to a guest operating system could leverage this flaw to escalate privileges and execute malicious code on the underlying host system, potentially compromising the entire virtualization infrastructure. This represents a significant bypass of virtualization security controls, as the guest-to-host privilege escalation could enable attackers to access sensitive data, modify system configurations, or establish persistent backdoors. The vulnerability affects critical VMware products including ESXi 6.5, ESXi 6.0 U3, U2, U1, and ESXi 5.5, along with VMware Workstation Pro/Player 12.x and Fusion Pro/Fusion 8.x versions prior to the specified patch releases. The exploitability of this vulnerability aligns with ATT&CK technique T1055.001 for privilege escalation and T1070 for bypassing security controls within virtualized environments.
Organizations should immediately implement the vendor-provided patches for all affected VMware products, including ESXi650-201703410-SG, ESXi600-201703401-SG, ESXi600-201703403-SG, ESXi600-201703402-SG, ESXi550-201703401-SG, and corresponding patches for Workstation Pro/Player 12.5.5 and Fusion Pro/Fusion 8.5.6. Additionally, implementing network segmentation, monitoring for unusual USB device activity, and restricting guest operating system privileges can provide additional defensive layers. The vulnerability highlights the critical importance of maintaining up-to-date virtualization software and demonstrates how flaws in hypervisor components can undermine the fundamental security model of virtualized environments. Security teams should also consider implementing intrusion detection systems to monitor for potential exploitation attempts and establish incident response procedures for handling potential privilege escalation events within virtualized infrastructures.