CVE-2017-11830 in Windows
Summary
by MITRE
Device Guard in Windows 10 Gold, 1511, 1607, 1703, and 1709, Windows Server 2016, and Windows Server, version 1709 allows an attacker to make an unsigned file appear to be signed, due to a security feature bypass, aka "Device Guard Security Feature Bypass Vulnerability".
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Analysis
by VulDB Data Team • 01/23/2021
The CVE-2017-11830 vulnerability represents a critical security flaw in Microsoft's Device Guard implementation across multiple Windows 10 and Windows Server versions. This vulnerability specifically targets the code integrity verification mechanisms that Device Guard employs to prevent execution of unsigned code. The flaw allows attackers to bypass the security checks that should validate digital signatures, enabling malicious actors to make unsigned files appear as if they are properly signed. This security bypass affects Windows 10 versions 1511, 1607, 1703, and 1709, as well as Windows Server 2016 and Windows Server version 1709, creating a widespread exposure across enterprise environments that rely on Device Guard for code integrity protection.
The technical root cause of this vulnerability stems from how Device Guard handles certificate validation and signature verification processes. When Device Guard processes code integrity policies, it fails to properly validate the authenticity of digital signatures, allowing attackers to manipulate the signature verification process. This creates a scenario where unsigned malicious code can be presented with forged digital signatures that appear legitimate to the system's security mechanisms. The vulnerability specifically exploits weaknesses in the certificate chain validation and signature enforcement components of Device Guard, enabling attackers to circumvent the intended security controls that should prevent execution of untrusted code. This flaw operates at the kernel level where code integrity policies are enforced, making it particularly dangerous as it undermines fundamental security controls that protect against malicious software execution.
The operational impact of this vulnerability extends far beyond simple code execution bypass, as it fundamentally compromises the integrity of Windows security controls. Attackers can leverage this vulnerability to execute arbitrary code without proper digital signatures, potentially leading to complete system compromise and persistent access within target environments. The vulnerability's broad scope affects both client and server operating systems, creating potential attack vectors across enterprise networks where Device Guard is deployed for security policy enforcement. Organizations that rely on Device Guard to prevent execution of unsigned applications, scripts, or binaries face significant risk, as this vulnerability essentially neutralizes the security benefits that Device Guard was designed to provide. The attack surface is particularly concerning in environments where Device Guard is used as a primary defense mechanism against advanced persistent threats and zero-day exploits.
Mitigation strategies for CVE-2017-11830 should focus on immediate patch deployment and enhanced monitoring of code integrity policies. Microsoft released security updates that address the signature validation bypass, and organizations must prioritize applying these patches across all affected Windows 10 and Windows Server versions. Additionally, administrators should implement enhanced monitoring of Device Guard policy enforcement and signature validation events to detect potential exploitation attempts. The vulnerability aligns with ATT&CK technique T1134 which covers process injection and code integrity bypass methods, making it particularly relevant for threat hunting activities. Organizations should also consider implementing additional security controls such as application control policies, enhanced logging, and regular security assessments of their Device Guard configurations. The vulnerability demonstrates the importance of maintaining up-to-date security patches and proper configuration management, as it represents a failure in the security validation process that could have been prevented through timely patching. Security teams should also review their existing Device Guard policies to ensure they are properly configured and that signature validation is functioning as intended, since this vulnerability essentially renders the signature verification component ineffective.