CVE-2019-0637 in Windows
Summary
by MITRE
A security feature bypass vulnerability exists when Windows Defender Firewall incorrectly applies firewall profiles to cellular network connections, aka 'Windows Defender Firewall Security Feature Bypass Vulnerability'.
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Analysis
by VulDB Data Team • 07/13/2024
The vulnerability identified as CVE-2019-0637 represents a critical security feature bypass in Microsoft Windows Defender Firewall that affects multiple Windows versions including Windows 10, Windows Server 2016, and Windows Server 2019. This flaw stems from improper handling of firewall profile application when cellular network connections are established, creating a pathway for malicious actors to circumvent network security controls. The vulnerability specifically impacts how Windows Defender Firewall manages network profiles for cellular interfaces, which are typically more restrictive than wired connections due to their inherent mobility and potential security risks. This misconfiguration allows unauthorized network access that should otherwise be blocked by firewall policies, fundamentally undermining the network protection mechanisms that organizations rely upon for perimeter security.
The technical root cause of this vulnerability lies in the Windows Defender Firewall service's failure to correctly identify and apply appropriate firewall profiles to cellular network interfaces. When a device connects to a cellular network, the system should automatically apply the appropriate security profile that restricts incoming connections and enforces strict access controls. However, the flaw allows the firewall to incorrectly apply less restrictive profiles or fail to apply any profile at all, enabling attackers to establish connections that would normally be blocked. This behavior creates a persistent security gap where network traffic can traverse the firewall without proper inspection or filtering, particularly affecting mobile devices and laptops that frequently connect to cellular networks. The vulnerability operates at the network layer and can be exploited through various attack vectors that leverage the misapplied firewall profiles to establish unauthorized communication channels.
The operational impact of CVE-2019-0637 extends beyond simple network access issues, creating significant risks for enterprise environments where cellular connectivity is common among mobile workers and IoT devices. Organizations using Windows-based infrastructure face potential data exfiltration, lateral movement, and persistent access points that attackers can exploit to maintain footholds within networks. The vulnerability is particularly concerning for environments with strict network segmentation policies, where cellular connections should be isolated from sensitive internal resources. Mobile workers using Windows devices for corporate purposes become potential attack vectors, as their cellular connections may bypass the network security controls that protect against external threats. This security bypass can enable attackers to establish command and control channels, conduct reconnaissance, or deploy additional malicious payloads without detection, making the vulnerability particularly dangerous in threat hunting and incident response scenarios.
Mitigation strategies for CVE-2019-0637 should focus on immediate patch deployment through Microsoft's regular security updates, with particular attention to ensuring all Windows 10 and Windows Server systems are updated to versions containing the fix. Network administrators should implement additional monitoring of cellular network traffic patterns and establish baseline behaviors for network connections to detect anomalous activity that may indicate exploitation attempts. Organizations should consider implementing network segmentation strategies that limit cellular connectivity to specific network zones and enforce strict access controls for any devices that connect through cellular interfaces. The vulnerability aligns with CWE-284, which addresses improper access control in software systems, and maps to ATT&CK technique T1071.004 for application layer protocol communication over cellular networks. Additional defensive measures include configuring Windows Defender Firewall with advanced settings to enforce strict profile application for all network interfaces and implementing network traffic analysis tools that can detect unauthorized connections that bypass expected firewall behavior. Organizations should also consider deploying endpoint detection and response solutions that can identify and alert on suspicious network activities that may indicate exploitation of this vulnerability.