CVE-2001-0016 in Windows
Summary
by MITRE
NTLM Security Support Provider (NTLMSSP) service does not properly check the function number in an LPC request, which could allow local users to gain administrator level access.
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Analysis
by VulDB Data Team • 10/11/2025
The vulnerability identified as CVE-2001-0016 resides within the NTLM Security Support Provider implementation on Microsoft Windows systems, specifically affecting the Local Procedure Call (LPC) communication mechanism used for authentication processes. This flaw manifests in the NTLMSSP service which handles NTLM authentication requests between client and server components, creating a critical security gap that can be exploited by local attackers to escalate privileges. The vulnerability stems from insufficient validation of function numbers within LPC requests, allowing malicious code to manipulate authentication flows and potentially gain administrative control over affected systems.
The technical root cause of this vulnerability lies in the improper validation of function numbers within the LPC request structure that NTLMSSP processes during authentication operations. When a client system attempts to authenticate using NTLM, it communicates with the NTLMSSP service through LPC messages containing specific function codes that instruct the service on how to process the authentication request. The flaw occurs because the service fails to properly verify that these function numbers correspond to legitimate authentication operations, enabling an attacker to craft malicious LPC requests with modified function numbers that bypass normal authentication checks. This weakness operates at the kernel level within the Windows security subsystem, making it particularly dangerous as it can be exploited without requiring network connectivity or remote access to the system.
The operational impact of CVE-2001-0016 is severe and potentially catastrophic for affected systems, as local attackers who can execute code on a target machine can leverage this vulnerability to achieve administrator level access without requiring legitimate credentials or network-based exploitation. This privilege escalation vulnerability allows attackers to gain full control over the compromised system, potentially enabling them to install malware, modify system files, access sensitive data, or establish persistent backdoors. The local nature of the attack means that an attacker only needs to have user-level access to the system to exploit this vulnerability, making it particularly dangerous in environments where user accounts may have elevated privileges or where privilege escalation opportunities exist. The vulnerability affects Windows 2000 and Windows NT 4.0 systems, with the potential for widespread impact across enterprise environments where these older operating systems may still be deployed.
This vulnerability aligns with CWE-264, which describes "Permissions, Privileges, and Access Controls" weaknesses, specifically addressing insufficient validation of function parameters within system services. The attack pattern corresponds to techniques described in the ATT&CK framework under privilege escalation tactics, particularly focusing on local privilege escalation methods that exploit service vulnerabilities. Microsoft addressed this vulnerability through security updates that implemented proper validation of LPC function numbers within the NTLMSSP service, requiring all authentication requests to undergo strict parameter verification before processing. Organizations should implement comprehensive patch management procedures to ensure all systems receive the necessary security updates, while also monitoring for potential exploitation attempts through system logs and security information event management systems. The vulnerability serves as a critical reminder of the importance of proper input validation and parameter checking within security-critical system components, particularly those operating at kernel level where privilege escalation opportunities can lead to complete system compromise.