CVE-2000-0404 in Windows
Summary
by MITRE
The CIFS Computer Browser service allows remote attackers to cause a denial of service by sending a ResetBrowser frame to the Master Browser, aka the "ResetBrowser Frame" vulnerability.
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Analysis
by VulDB Data Team • 04/21/2026
The CVE-2000-0404 vulnerability represents a critical denial of service flaw within the Common Internet File System implementation that specifically targets the Computer Browser service functionality. This vulnerability exploits the broadcast-based communication mechanism used by Windows networking protocols to maintain browser lists and master browser elections. The CIFS protocol relies on a hierarchical browser service structure where computers advertise their presence and capabilities to form a network browsing topology, with a designated Master Browser maintaining the authoritative list of available resources. The vulnerability arises from insufficient input validation and error handling within the ResetBrowser frame processing mechanism, which is part of the NetBIOS Session Service communication layer that underpins CIFS operations.
The technical flaw manifests when a remote attacker crafts and sends a malformed ResetBrowser frame to the current Master Browser within a CIFS network segment. This specific frame type is designed to reset and refresh the browser list maintained by the Master Browser service, but the vulnerability occurs because the system fails to properly validate the frame content and parameters before processing. The ResetBrowser frame contains information about the sending computer's browser capabilities and network presence, but when this frame is malformed or exceeds expected parameter limits, the Master Browser service enters an unstable state. This processing failure causes the Master Browser to either crash or become unresponsive, effectively disrupting the entire browsing service within the local network segment. The vulnerability operates at the application layer of the OSI model and specifically targets the NetBIOS Session Service implementation that Windows operating systems use to provide file and print sharing capabilities over network connections.
The operational impact of CVE-2000-0404 extends far beyond simple service disruption as it can completely瘫痪 network browsing functionality for all users within the affected segment. When the Master Browser service becomes unavailable, users lose the ability to discover shared resources, view network drives, or access printers that rely on the browser service for name resolution. This affects not only basic file sharing operations but also authentication mechanisms that depend on network browsing for domain controller discovery and resource location. The vulnerability particularly impacts environments with multiple Windows systems that depend on the browser service for network communication, including small office networks, enterprise segments, and any configuration where automatic browser election occurs. Network administrators may experience cascading failures as the absence of a functional Master Browser prevents proper network topology maintenance and can lead to extended service outages that require manual intervention to restore.
Mitigation strategies for this vulnerability must address both immediate protection and long-term network architecture improvements. The most direct approach involves applying the Microsoft security patch released in conjunction with the vulnerability disclosure, which corrects the input validation errors in the ResetBrowser frame processing logic. Organizations should also implement network segmentation to isolate critical services from potential attack vectors, particularly by configuring firewalls to block unsolicited NetBIOS traffic on ports 137 and 138. Network administrators should consider disabling the Computer Browser service on systems where it is not required, as many modern network configurations no longer depend on this legacy functionality. The vulnerability aligns with CWE-129 Input Validation and CWE-20 Improper Input Validation categories, and represents a classic example of how broadcast-based network protocols can be exploited for denial of service attacks. From an ATT&CK framework perspective, this vulnerability maps to T1499.004 Network Denial of Service and T1071.004 Application Layer Protocol, demonstrating how legacy network protocols can create persistent security weaknesses that require both patch management and architectural considerations for comprehensive protection.