CVE-2001-0540 in Windows
Summary
by MITRE
Memory leak in Terminal servers in Windows NT and Windows 2000 allows remote attackers to cause a denial of service (memory exhaustion) via a large number of malformed Remote Desktop Protocol (RDP) requests to port 3389.
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Analysis
by VulDB Data Team • 10/05/2025
The vulnerability described in CVE-2001-0540 represents a critical memory management flaw affecting Microsoft Windows NT and Windows 2000 terminal server implementations. This issue manifests as a memory leak within the Remote Desktop Protocol (RDP) stack, specifically when processing malformed RDP requests directed at the default terminal server port 3389. The vulnerability operates at the network protocol level, exploiting weaknesses in how the Windows terminal server handles incoming connection requests and session management. Attackers can leverage this flaw by sending a large volume of carefully crafted malformed RDP packets to exhaust available memory resources on the targeted system, ultimately leading to system instability and denial of service conditions.
The technical root cause of this vulnerability stems from inadequate input validation and memory management within the RDP implementation of the affected Windows versions. When the terminal server receives malformed RDP requests, it fails to properly clean up allocated memory resources during error handling procedures, resulting in gradual memory consumption over time. This memory leak behavior is particularly dangerous because it can be exploited remotely without requiring authentication, making it an attractive target for automated denial of service attacks. The vulnerability specifically impacts the Windows NT 4.0 and Windows 2000 terminal server editions, where the RDP protocol implementation lacks sufficient safeguards against malformed packet processing. According to CWE standards, this vulnerability maps to CWE-401: Improper Release of Memory and CWE-122: Heap Overflow, indicating both memory leak and heap-based memory corruption issues within the system's memory management subsystem.
The operational impact of CVE-2001-0540 extends beyond simple service disruption to potentially compromise entire network infrastructure availability. Organizations running vulnerable terminal servers face significant risk of unauthorized denial of service attacks that can render critical business applications inaccessible to legitimate users. The remote exploit capability means that attackers can target systems from anywhere on the network without requiring physical access or prior authentication credentials, making this vulnerability particularly dangerous in enterprise environments where terminal servers are commonly exposed to external networks. System administrators may observe gradual performance degradation followed by complete service unavailability as memory resources become exhausted, with the affected systems requiring manual restart to restore normal operations. This vulnerability directly aligns with ATT&CK technique T1499.004: Endpoint Denial of Service, which encompasses methods targeting system resources to prevent legitimate use of services.
Mitigation strategies for this vulnerability require immediate implementation of security patches provided by Microsoft, specifically the security updates released for Windows NT 4.0 and Windows 2000 terminal servers. Network administrators should implement firewall rules to restrict access to port 3389 from untrusted networks, as the vulnerability can be exploited remotely without authentication. Additional protective measures include implementing intrusion detection systems to monitor for unusual traffic patterns on port 3389 and configuring automatic system monitoring to detect memory exhaustion conditions. Organizations should also consider implementing network segmentation to isolate terminal server resources and reduce the attack surface. The vulnerability highlights the importance of proper memory management in network service implementations and underscores the necessity of thorough input validation and error handling procedures in system design. Security monitoring should include regular memory usage checks and automated alerts for systems showing signs of memory exhaustion, particularly in environments where terminal services are actively used.