CVE-2000-1003 in Windows
Summary
by MITRE
NETBIOS client in Windows 95 and Windows 98 allows a remote attacker to cause a denial of service by changing a file sharing service to return an unknown driver type, which causes the client to crash.
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Analysis
by VulDB Data Team • 04/14/2019
The vulnerability described in CVE-2000-1003 represents a classic denial of service flaw affecting the NETBIOS client implementation in Windows 95 and Windows 98 operating systems. This issue stems from insufficient input validation within the file sharing service component that handles network resource access. The vulnerability specifically targets the client-side processing of network file sharing connections where the client expects certain driver types but encounters unexpected or malformed responses from the server. The flaw exists in the Windows 9x operating system family's legacy networking stack, which was designed primarily for internal corporate networks rather than the increasingly complex and potentially hostile internet environment. This vulnerability demonstrates the inherent security limitations of older operating systems that were not initially designed with robust protection mechanisms against malicious network traffic.
The technical exploitation of this vulnerability occurs when a remote attacker crafts a malicious response to a file sharing request that contains an unknown or invalid driver type identifier. When the vulnerable Windows 95 or 98 client receives this malformed response, the NETBIOS client component fails to properly handle the unexpected data structure and subsequently crashes or becomes unresponsive. The client application essentially encounters a buffer overflow condition or invalid memory access when processing the unexpected driver type, leading to a complete system crash or hang that requires manual intervention to restore normal operation. This behavior aligns with CWE-125, which describes out-of-bounds read conditions, and CWE-129, which covers insufficient validation of array indices, both of which are common in legacy networking implementations. The attack vector requires only network access to the target system and does not require authentication, making it particularly dangerous in shared network environments.
The operational impact of this vulnerability extends beyond simple service disruption, as it affects the core networking capabilities of affected systems. When a Windows 95 or 98 client crashes due to this vulnerability, users lose access to shared network resources and may experience complete system instability that affects other network-dependent applications. In corporate environments where these older systems might still be operational, this vulnerability could lead to significant productivity losses and increased administrative overhead as IT staff must respond to system crashes and restore normal operations. The vulnerability also demonstrates how legacy systems can become security liabilities when deployed in modern network environments where they face threats from unauthenticated remote attackers. This issue exemplifies the ATT&CK technique T1499.004, which involves network denial of service attacks against remote systems, and highlights the importance of maintaining up-to-date security patches for legacy systems.
Mitigation strategies for this vulnerability primarily involve implementing network segmentation and access controls to prevent unauthorized remote access to affected systems. Organizations should consider deploying network firewalls to block unnecessary NETBIOS traffic and restrict access to file sharing services from untrusted networks. The most effective long-term solution involves upgrading from Windows 95 and Windows 98 to supported operating systems that have proper security controls and regular security updates. Network administrators should also implement monitoring solutions to detect unusual network traffic patterns that might indicate exploitation attempts. Additionally, disabling unnecessary file sharing services and implementing strong authentication mechanisms can reduce the attack surface for this and similar vulnerabilities. The vulnerability underscores the critical importance of maintaining secure network configurations and the dangers of continuing to operate unsupported legacy systems in production environments without proper compensating controls.