CVE-2019-0695 in Windows
Summary
by MITRE
A denial of service vulnerability exists when Microsoft Hyper-V on a host server fails to properly validate input from a privileged user on a guest operating system, aka 'Windows Hyper-V Denial of Service Vulnerability'. This CVE ID is unique from CVE-2019-0690, CVE-2019-0701.
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Analysis
by VulDB Data Team • 08/01/2023
The vulnerability identified as CVE-2019-0695 represents a critical denial of service weakness within Microsoft Hyper-V hypervisor technology that specifically affects host server systems. This flaw manifests when Hyper-V fails to adequately validate input data originating from privileged user contexts within guest operating systems, creating a pathway for malicious actors to disrupt normal system operations. The vulnerability is particularly concerning because it leverages the trusted relationship between host and guest environments, where guest users with elevated privileges can potentially exploit this weakness to cause system instability. The issue impacts various Microsoft Windows Server versions that incorporate Hyper-V virtualization capabilities, making it a widespread concern across enterprise environments that rely on virtualized infrastructure for their operations.
The technical mechanism underlying this vulnerability stems from insufficient input validation procedures within the Hyper-V host component when processing requests from guest operating systems. When a privileged user executes specific operations within a guest VM, the hypervisor fails to properly sanitize or verify the legitimacy of the input parameters being transmitted across the virtualization boundary. This validation failure creates a condition where malformed or specially crafted input can cause the Hyper-V host to enter an unstable state or completely crash, resulting in denial of service for all virtual machines hosted on that system. The vulnerability operates at the hypervisor level, meaning that successful exploitation can affect multiple guest operating systems simultaneously, potentially causing cascading failures throughout the virtualized infrastructure. According to CWE classification, this vulnerability aligns with CWE-20: Improper Input Validation, which specifically addresses the lack of proper validation of input data that can lead to system instability and denial of service conditions.
The operational impact of CVE-2019-0695 extends beyond simple service disruption, as it can compromise the integrity of entire virtualized environments. Organizations utilizing Hyper-V for mission-critical workloads face significant risk of operational downtime when this vulnerability is exploited, potentially leading to data loss, service interruptions, and financial consequences. The vulnerability's exploitation typically requires a privileged user context within a guest operating system, which means that attackers must first gain access to a guest VM or have legitimate administrative access to compromise the system. However, the elevated privileges required for exploitation also make this vulnerability particularly dangerous when combined with other attack vectors or when organizations have compromised administrative credentials. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and denial of service operations, potentially allowing adversaries to maintain persistent access while simultaneously disrupting system availability. The impact is exacerbated in cloud environments where multiple tenants share the same physical hardware, as a single compromised guest VM could potentially affect other tenants' systems through the hypervisor layer.
Mitigation strategies for CVE-2019-0695 primarily focus on applying Microsoft security patches and updates that address the specific input validation deficiencies within the Hyper-V implementation. Organizations should prioritize immediate deployment of the relevant security updates provided by Microsoft to remediate this vulnerability across their virtualized infrastructure. Additionally, implementing network segmentation and access controls can help limit the potential impact of exploitation by reducing the attack surface available to privileged users within guest environments. System administrators should also consider implementing monitoring solutions that can detect anomalous behavior patterns consistent with denial of service attempts, enabling rapid response to potential exploitation attempts. Regular vulnerability assessments and penetration testing of virtualized environments can help identify additional weaknesses that may compound the risk associated with this vulnerability. Organizations should also review their privileged access management policies to ensure that administrative privileges are properly restricted and monitored, as the vulnerability requires elevated guest user privileges to be effectively exploited. The remediation process should include comprehensive testing of patches in non-production environments before deployment to ensure that updates do not introduce compatibility issues with existing virtualized workloads.