CVE-2012-0174 in Windows
Summary
by MITRE
Windows Firewall in tcpip.sys in Microsoft Windows Vista SP2, Windows Server 2008 SP2, R2, and R2 SP1, and Windows 7 Gold and SP1 does not properly enforce firewall rules for outbound broadcast packets, which allows remote attackers to obtain potentially sensitive information by observing broadcast traffic on a local network, aka "Windows Firewall Bypass Vulnerability."
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Analysis
by VulDB Data Team • 03/24/2021
The vulnerability described in CVE-2012-0174 represents a critical flaw in Microsoft Windows firewall implementation that specifically affects the tcpip.sys kernel driver component. This issue impacts multiple Windows operating systems including Vista SP2, Windows Server 2008 SP2 and R2 variants, and Windows 7 Gold and SP1 releases. The fundamental problem lies in the improper enforcement of firewall rules for outbound broadcast packets, creating a significant security gap in network traffic management. The vulnerability enables remote attackers to bypass firewall protections and observe broadcast traffic on local networks, potentially exposing sensitive information that should otherwise be restricted by firewall policies.
The technical flaw manifests in the tcpip.sys driver's handling of network packet filtering for broadcast traffic. When Windows Firewall processes outbound broadcast packets, the system fails to properly validate or enforce the configured firewall rules, allowing these packets to traverse the network stack without appropriate security checks. This bypass mechanism specifically affects broadcast traffic that would normally be filtered or restricted by firewall policies, creating a pathway for unauthorized network monitoring and information disclosure. The vulnerability is particularly concerning because broadcast traffic often contains network discovery information, service announcements, and other potentially sensitive data that should remain protected within local network segments.
From an operational impact perspective, this vulnerability allows attackers to perform network reconnaissance and information gathering activities that would normally be blocked by firewall configurations. An attacker positioned on the same local network segment can observe broadcast traffic patterns and potentially extract sensitive information such as network service availability, device discovery information, and other metadata that could aid in further exploitation attempts. The vulnerability creates a persistent monitoring capability that can be leveraged for network mapping, service enumeration, and other reconnaissance activities that compromise network security posture. This issue particularly affects enterprise environments where broadcast traffic contains significant amounts of operational information that should remain confidential.
The security implications extend beyond simple information disclosure to potentially enable more sophisticated attack vectors. According to CWE classification, this vulnerability relates to improper enforcement of security policies in network stack components, specifically CWE-284 for improper access control and CWE-310 for cryptographic issues in network communications. The ATT&CK framework categorizes this under T1046 for network service scanning and T1049 for system network connections discovery, as attackers can leverage this bypass to map network services and identify potential targets. Organizations should implement immediate mitigations including applying Microsoft security patches, reviewing firewall configurations to minimize broadcast traffic exposure, and implementing network segmentation to limit the scope of potential exploitation.
Mitigation strategies should focus on both immediate patching and network-level defenses. Microsoft released security updates that address the tcpip.sys driver vulnerability, and organizations must ensure all affected systems receive these patches promptly. Network administrators should also consider implementing additional monitoring for unusual broadcast traffic patterns and review existing firewall rules to ensure they properly restrict broadcast traffic where possible. The vulnerability highlights the importance of proper kernel-level security implementation and demonstrates how low-level network stack components can create significant security gaps when not properly validated against security policies. Organizations should also conduct vulnerability assessments to identify other potential network stack issues that may create similar bypass opportunities.