CVE-2019-0635 in Windows
Summary
by MITRE
An information disclosure vulnerability exists when Windows Hyper-V on a host operating system fails to properly validate input from an authenticated user on a guest operating system, aka 'Windows Hyper-V Information Disclosure Vulnerability'.
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Analysis
by VulDB Data Team • 07/13/2024
The CVE-2019-0635 vulnerability represents a critical information disclosure flaw within Microsoft Windows Hyper-V hypervisor implementation that affects systems running Windows 10 and Windows Server 2016. This vulnerability stems from insufficient input validation mechanisms within the hypervisor's communication channels between host and guest operating systems, creating a potential pathway for unauthorized data exposure. The flaw specifically manifests when authenticated guest users can manipulate input parameters that should be strictly validated by the host hypervisor, leading to information leakage that could compromise system integrity and confidentiality. The vulnerability falls under the broader category of hypervisor-level security weaknesses that can undermine the fundamental isolation properties that virtualization environments are designed to maintain.
The technical exploitation of CVE-2019-0635 occurs through improper validation of guest-to-host communication protocols within the Hyper-V environment. When a guest operating system user successfully authenticates and submits crafted input data, the host hypervisor fails to adequately sanitize or validate these inputs before processing them. This validation failure allows for potential information disclosure through mechanisms such as memory dumps, register states, or other sensitive data that should remain isolated between virtual machines. The vulnerability is particularly concerning because it operates at the hypervisor layer where all virtual machine communications are processed, making it a prime target for attackers seeking to escalate privileges or extract confidential information from other virtual environments. According to CWE classification, this vulnerability maps to CWE-20: Improper Input Validation, which is a fundamental weakness in software design that allows malicious inputs to bypass validation checks. The attack vector aligns with ATT&CK technique T1059.001 for command and scripting interpreter and T1068 for exploit for privilege escalation.
The operational impact of CVE-2019-0635 extends beyond simple information disclosure, as it can enable more sophisticated attacks within virtualized environments. An attacker who successfully exploits this vulnerability could potentially access sensitive data from other virtual machines running on the same host, including credentials, system configurations, or application data. This compromise undermines the core security principle of virtual machine isolation that organizations rely upon for multi-tenant cloud environments and server consolidation strategies. The vulnerability affects organizations using Hyper-V in enterprise data centers, cloud service providers, and any environment where multiple virtual machines share the same physical host infrastructure. Given that Windows 10 and Windows Server 2016 were widely deployed at the time of the vulnerability disclosure, the potential attack surface was substantial across various organizational environments.
Mitigation strategies for CVE-2019-0635 primarily focus on applying Microsoft security patches and implementing additional operational controls. Organizations should immediately deploy the security update released by Microsoft as part of their regular patch management procedures, which addresses the input validation weakness in the Hyper-V hypervisor. Beyond patching, administrators should consider implementing network segmentation controls to limit guest-to-host communication where possible, and monitor for unusual patterns in virtual machine resource usage that might indicate exploitation attempts. The vulnerability highlights the importance of maintaining up-to-date hypervisor software and implementing robust security monitoring within virtualized environments. Organizations should also review their virtual machine configuration settings to ensure that unnecessary guest-to-host communication channels are disabled, reducing the potential attack surface for similar vulnerabilities. Additionally, implementing principle of least privilege controls for guest operating system users and regularly auditing virtual machine configurations can help minimize the impact of such vulnerabilities. The remediation process should include comprehensive testing of patches in non-production environments before deployment to ensure continued system stability and functionality.