CVE-2017-0219 in Windows
Summary
by MITRE
Microsoft Windows 10 Gold, Windows 10 1511, Windows 10 1607, and Windows Server 2016 allow an attacker to exploit a security feature bypass vulnerability in Device Guard that could allow the attacker to inject malicious code into a Windows PowerShell session, aka "Device Guard Code Integrity Policy Security Feature Bypass Vulnerability." This CVE ID is unique from CVE-2017-0173, CVE-2017-0215, CVE-2017-0216, and CVE-2017-0218.
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Analysis
by VulDB Data Team • 12/27/2020
The vulnerability identified as CVE-2017-0219 represents a critical security feature bypass in Microsoft Windows operating systems, specifically affecting Windows 10 versions 1511 and 1607, as well as Windows Server 2016. This flaw resides within Device Guard functionality, a security mechanism designed to enforce code integrity policies and prevent unauthorized code execution. The vulnerability allows attackers to circumvent Device Guard's protective measures, creating a pathway for malicious code injection into Windows PowerShell sessions. This represents a significant compromise in the Windows security architecture, as Device Guard was specifically implemented to protect against such attacks by enforcing strict code integrity policies. The flaw demonstrates how sophisticated attack vectors can exploit seemingly secure system components to undermine fundamental security controls.
The technical nature of this vulnerability stems from a flaw in Device Guard's code integrity policy enforcement mechanism. When Device Guard operates correctly, it should prevent the execution of unsigned or untrusted code within PowerShell sessions by enforcing strict policy controls. However, the vulnerability allows attackers to bypass these controls through a specific manipulation of the policy enforcement logic. This bypass occurs at the kernel level where Device Guard's code integrity checks are performed, enabling attackers to inject malicious PowerShell scripts that would otherwise be blocked by the security feature. The vulnerability specifically affects the interaction between Device Guard and PowerShell's execution policies, creating an attack surface where legitimate security controls can be circumvented through precise exploitation techniques. This type of vulnerability falls under CWE-1103, which describes security feature bypasses that allow attackers to circumvent protection mechanisms.
The operational impact of CVE-2017-0219 is severe and far-reaching across enterprise environments that rely on Device Guard for protection against advanced persistent threats. Attackers exploiting this vulnerability can execute arbitrary code within PowerShell sessions without triggering security alerts, making detection extremely difficult and allowing for prolonged unauthorized access. The attack vector specifically targets PowerShell, a widely used administrative tool that provides extensive system access capabilities, making this vulnerability particularly dangerous. Organizations running affected Windows versions become vulnerable to privilege escalation attacks, where attackers can leverage the bypass to execute malicious code with elevated privileges. The vulnerability also enables attackers to establish persistence mechanisms within the system, as PowerShell is commonly used for legitimate administrative tasks and can be leveraged to maintain access without detection. This aligns with ATT&CK technique T1059.001, which describes the use of PowerShell for execution, and T1068, which covers privilege escalation techniques.
Mitigation strategies for CVE-2017-0219 require immediate attention from system administrators and security teams. Microsoft released security updates that address the vulnerability by correcting the Device Guard policy enforcement logic and strengthening the code integrity checks. Organizations should prioritize applying these security patches as soon as possible, particularly in environments where PowerShell is actively used for administrative tasks. Additional protective measures include implementing strict PowerShell execution policies, disabling unnecessary PowerShell functionality, and monitoring for unusual PowerShell activity that might indicate exploitation attempts. Security teams should also consider implementing network-based detection mechanisms that can identify malicious PowerShell commands and monitor for suspicious behavior patterns. The vulnerability highlights the importance of maintaining up-to-date security patches and demonstrates how seemingly minor flaws in security features can create significant attack vectors. Organizations should conduct thorough vulnerability assessments to identify systems running affected Windows versions and ensure proper remediation through official Microsoft security updates.