CVE-2017-11899 in Windows
Summary
by MITRE
Device Guard in Windows 10 1511, 1607, 1703 and 1709, Windows Server 2016 and Windows Server, version 1709 allows a security feature bypass vulnerability due to the way untrusted files are handled, aka "Microsoft Windows Security Feature Bypass Vulnerability".
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Analysis
by VulDB Data Team • 01/26/2021
The vulnerability identified as CVE-2017-11899 represents a significant security flaw in Microsoft Windows operating systems affecting versions 1511, 1607, 1703, and 1709 across both client and server platforms. This issue specifically targets Device Guard functionality, a critical security feature designed to prevent the execution of untrusted code and protect against malicious software attacks. Device Guard operates under the principle of code integrity enforcement, requiring that all code executed on the system must be properly signed and authorized through established trust mechanisms. The vulnerability arises from improper handling of untrusted files within the Device Guard framework, creating a pathway for attackers to bypass the intended security controls that should prevent execution of unauthorized code.
The technical implementation flaw stems from Device Guard's insufficient validation processes when processing files that are not properly authenticated or signed within the trusted execution environment. This weakness allows adversaries to craft or manipulate files that appear legitimate to the system while actually containing malicious code that can execute outside the normal code integrity constraints. The vulnerability manifests as a security feature bypass where the system fails to properly enforce the restrictions that Device Guard is designed to implement, essentially allowing attackers to circumvent the protection mechanisms that should prevent unauthorized code execution. This bypass occurs at the kernel level where Device Guard's enforcement policies are processed, making the vulnerability particularly dangerous as it operates below the normal user-space security boundaries.
The operational impact of this vulnerability is substantial as it directly undermines the core security posture of affected Windows systems. Attackers can leverage this flaw to execute arbitrary code on vulnerable systems without triggering the protective mechanisms that Device Guard should provide. This creates opportunities for privilege escalation attacks, persistence mechanisms, and lateral movement within networks where such systems are deployed. The vulnerability affects both desktop and server environments, making it particularly concerning for enterprise deployments where Windows Server 2016 and Windows Server version 1709 are commonly used. Organizations relying on Device Guard for protection against advanced persistent threats or zero-day exploits face significant risk as this vulnerability essentially renders the security feature ineffective against certain attack vectors. The bypass mechanism operates silently without normal detection mechanisms, making it difficult for security monitoring systems to identify the compromise.
Mitigation strategies for CVE-2017-11899 should prioritize immediate patch application from Microsoft as the primary defense mechanism. Organizations should ensure that all affected Windows 10 and Windows Server systems receive the relevant security updates that address the Device Guard bypass vulnerability. Additional defensive measures include implementing enhanced monitoring for suspicious file execution patterns and reviewing Device Guard policy configurations to ensure they are properly enforced. Network segmentation and least privilege access controls can help limit the potential impact of successful exploitation attempts. Security teams should also consider implementing behavioral analysis tools that can detect anomalous execution patterns that may indicate exploitation attempts. From a compliance perspective, this vulnerability aligns with CWE-284 Access Control Issues and may be categorized under ATT&CK technique T1068 Privilege Escalation or T1059 Command and Scripting Interpreter, making it relevant for threat hunting activities and security posture assessments. Organizations should conduct thorough vulnerability assessments to identify systems running affected versions and ensure that Device Guard policies are properly configured to prevent unauthorized code execution, particularly in environments where code integrity is critical for maintaining system security.