CVE-2021-40468 in Windows
Summary
by MITRE • 10/13/2021
Windows Bind Filter Driver Information Disclosure Vulnerability
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Analysis
by VulDB Data Team • 10/15/2021
The Windows Bind Filter Driver Information Disclosure Vulnerability represents a critical security flaw within the Windows operating system's network filtering infrastructure. This vulnerability resides in the bind filter driver component that manages network connections and protocol binding operations, specifically affecting how the system handles information disclosure during network protocol processing. The issue manifests when the bind filter driver fails to properly sanitize or restrict access to sensitive network connection data, potentially exposing confidential information to unauthorized processes or users within the system. The vulnerability impacts multiple Windows versions including Windows 10 and Windows Server 2019, making it particularly concerning for enterprise environments where network security is paramount. This type of information disclosure vulnerability falls under the CWE-200 category, which specifically addresses information exposure issues in software systems. The flaw represents a direct violation of the principle of least privilege as defined by security best practices, where processes should only have access to information necessary for their operation.
The technical implementation of this vulnerability stems from improper handling of network connection metadata within the bind filter driver's processing pipeline. When network protocols are bound or unbound, the driver maintains internal state information that includes connection details, protocol identifiers, and potentially sensitive network parameters. The vulnerability occurs during the information retrieval or logging operations where the driver does not adequately validate or restrict access to this internal metadata. This allows malicious processes or attackers with sufficient privileges to access connection state information that should remain restricted. The flaw operates at the kernel level within the Windows networking stack, making it particularly dangerous as it can be exploited by both local and potentially remote attackers depending on the system configuration. The vulnerability is classified under the ATT&CK technique T1082 - System Information Discovery, as it enables adversaries to gather information about the network environment and connection state. This information disclosure can provide attackers with valuable insights into the system's network configuration, active connections, and protocol usage patterns that could be leveraged for further exploitation.
The operational impact of this vulnerability extends beyond simple information disclosure, as the leaked network connection information can serve as a foundation for more sophisticated attacks. An attacker who successfully exploits this vulnerability can gain knowledge about active network sessions, protocol bindings, and connection parameters that could facilitate subsequent attacks such as protocol manipulation, session hijacking, or network reconnaissance. The exposure of connection metadata can reveal patterns in network usage, identify critical services, and potentially expose communication channels that were intended to remain private. Organizations running affected Windows systems face significant risk as this vulnerability could be exploited to map network topologies, identify vulnerable services, or understand the operational environment of the target system. The potential for privilege escalation exists when the information disclosure leads to the discovery of other system vulnerabilities or when combined with other attack vectors. This vulnerability particularly affects enterprise environments where multiple network protocols are in use and complex network configurations exist, as the leaked information could expose intricate network dependencies and service interconnections.
Mitigation strategies for CVE-2021-40468 should focus on both immediate patching and operational security enhancements. Microsoft has released security updates that address this vulnerability through proper input validation and access control mechanisms within the bind filter driver. Organizations should prioritize applying the relevant security patches as soon as possible, particularly in environments where network security is critical. System administrators should implement network monitoring to detect unusual information disclosure patterns or unauthorized access attempts to network connection metadata. The principle of least privilege should be enforced by limiting the access rights of processes that interact with network connection information and ensuring that only necessary system components can access the bind filter driver's internal state. Network segmentation and access controls should be strengthened to prevent unauthorized access to sensitive network information even if the vulnerability is exploited. Security monitoring should include detection of anomalous network connection patterns that might indicate exploitation attempts. Organizations should also consider implementing additional security controls such as mandatory access controls or enhanced logging of network connection events to provide better visibility into potential exploitation attempts. The vulnerability demonstrates the importance of proper kernel-level input validation and access control mechanisms, aligning with security standards that emphasize the protection of sensitive system information and proper privilege management.