CVE-2017-8715 in Windows
Summary
by MITRE
The Microsoft Device Guard on Microsoft Windows 10 Gold, 1511, 1607, and 1703, and Windows Server 2016 allows a security feature bypass by the way it handles Windows PowerShell sessions, aka "Windows Security Feature Bypass".
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Analysis
by VulDB Data Team • 09/11/2024
Microsoft Device Guard represents a critical security mechanism designed to prevent unauthorized code execution by enforcing strict application control policies and restricting the execution of potentially malicious PowerShell scripts. This vulnerability exists within the Windows 10 versions 1511, 1607, and 1703, as well as Windows Server 2016, specifically affecting how the system handles PowerShell sessions within the Device Guard framework. The flaw allows attackers to bypass the intended security controls through improper session handling mechanisms that fail to properly validate PowerShell execution contexts. This vulnerability operates at the intersection of application control and PowerShell execution policies, creating an exploitable gap where malicious code can execute with elevated privileges despite Device Guard protections. The security feature bypass occurs when PowerShell sessions are established and maintained, allowing adversaries to circumvent the intended restrictions on script execution and binary loading.
The technical implementation of this vulnerability stems from insufficient validation of PowerShell session contexts within Device Guard's enforcement mechanisms. When PowerShell sessions are created, the system fails to properly verify that these sessions adhere to the established code integrity policies, enabling attackers to leverage legitimate PowerShell functionality to execute unauthorized code. This flaw directly relates to CWE-284, which addresses improper access control, and CWE-345, concerning insufficient verification of data integrity. The vulnerability exploits the gap between the intended security model and actual implementation, allowing malicious actors to establish PowerShell sessions that bypass the application control restrictions. Attackers can utilize this bypass to execute malicious scripts or binaries that would normally be blocked by Device Guard's policy enforcement mechanisms, effectively neutralizing the security controls designed to prevent unauthorized code execution.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it fundamentally undermines the trust model that Device Guard establishes for Windows environments. Organizations relying on Device Guard for protection against malicious PowerShell attacks face significant risk when this vulnerability exists, as it allows attackers to execute arbitrary code within the bounds of seemingly secure PowerShell sessions. This bypass enables threat actors to perform reconnaissance, establish persistence, and conduct further exploitation without detection by traditional Device Guard mechanisms. The vulnerability affects the core security posture of Windows 10 and Server 2016 environments, particularly in enterprise settings where Device Guard is deployed to prevent advanced persistent threats. From an ATT&CK framework perspective, this vulnerability maps to T1059.001 for PowerShell execution and T1068 for local privilege escalation, representing a critical weakness in the execution and privilege escalation phases of the attack lifecycle.
Mitigation strategies for this vulnerability require immediate patch application through Microsoft's security updates, as the flaw exists in the core operating system components that control PowerShell session handling. Organizations should implement additional monitoring for unusual PowerShell activity and session creation patterns that may indicate exploitation attempts. Network segmentation and principle of least privilege enforcement can help limit the potential impact if exploitation occurs. Security teams should also conduct comprehensive assessments of existing Device Guard policies to ensure they remain effective against this bypass mechanism. The vulnerability highlights the importance of maintaining up-to-date security controls and the need for continuous monitoring of security features to prevent exploitation of implementation gaps. Regular security assessments and vulnerability scanning should include verification that Device Guard policies are properly enforced, particularly in environments where PowerShell execution is permitted but restricted.