CVE-2019-8934 in QEMU
Summary
by MITRE
hw/ppc/spapr.c in QEMU through 3.1.0 allows Information Exposure because the hypervisor shares the /proc/device-tree/system-id and /proc/device-tree/model system attributes with a guest.
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Analysis
by VulDB Data Team • 10/26/2024
The vulnerability described in CVE-2019-8934 represents a critical information disclosure flaw within the QEMU virtualization platform that affects versions through 3.1.0. This issue resides in the powerpc spapr (shared processor abstract platform representation) implementation where the hypervisor inadvertently exposes sensitive system identification and model information to guest operating systems through proc filesystem entries. The vulnerability specifically impacts the hypervisor's handling of device tree attributes, particularly the system-id and model parameters that are typically reserved for system-level information and should remain isolated from guest environments.
The technical flaw stems from improper access control mechanisms within QEMU's spapr implementation where the hypervisor fails to properly isolate system-level device tree attributes from guest virtual machines. When a guest operating system attempts to access /proc/device-tree/system-id and /proc/device-tree/model paths, the hypervisor provides direct access to these attributes without adequate sanitization or access restriction. This allows guest operating systems to read information that should remain confidential and protected at the hypervisor level, effectively creating a information exposure condition that violates fundamental virtualization security principles.
The operational impact of this vulnerability extends beyond simple information disclosure as it enables attackers to gather sensitive system identification data that could be leveraged in subsequent attacks. An attacker controlling a guest virtual machine could potentially determine the exact hypervisor version, underlying hardware configuration, and system model information that would otherwise be hidden from guest environments. This information exposure creates opportunities for targeted attacks that could exploit known vulnerabilities specific to particular hypervisor versions or hardware configurations, potentially leading to privilege escalation or further compromise of the virtualized environment.
This vulnerability aligns with CWE-200, which addresses improper exposure of sensitive information, and represents a clear violation of the principle of least privilege in virtualization environments. The ATT&CK framework categorizes this as a technique for reconnaissance and information gathering where adversaries collect information about the target environment to plan subsequent attacks. Organizations running QEMU virtualization environments are particularly vulnerable as this flaw affects the core hypervisor functionality and impacts all virtual machines running on affected versions. The exposure of system identification data could enable attackers to craft more sophisticated attacks that target specific hypervisor implementations or hardware configurations, making this vulnerability particularly dangerous in enterprise environments where virtualization security is paramount.
The recommended mitigation involves upgrading to QEMU version 4.0.0 or later where the vulnerability has been addressed through proper access control mechanisms and device tree attribute isolation. Administrators should also implement additional monitoring to detect unauthorized access to sensitive system information within virtual environments and consider implementing network segmentation to limit the potential impact of information disclosure. Organizations should conduct thorough vulnerability assessments of their virtualization environments to identify any other potential information exposure issues and ensure proper isolation between guest operating systems and hypervisor-level information.