CVE-2000-1039 in Windows
Summary
by MITRE
Various TCP/IP stacks and network applications allow remote attackers to cause a denial of service by flooding a target host with TCP connection attempts and completing the TCP/IP handshake without maintaining the connection state on the attacker host, aka the "NAPTHA" class of vulnerabilities. NOTE: this candidate may change significantly as the security community discusses the technical nature of NAPTHA and learns more about the affected applications. This candidate is at a higher level of abstraction than is typical for CVE.
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Analysis
by VulDB Data Team • 10/11/2025
The CVE-2000-1039 vulnerability represents a significant class of denial of service attacks targeting TCP/IP implementations across various network applications and operating systems. This vulnerability category, commonly referred to as the "NAPTHA" class of vulnerabilities, exploits fundamental weaknesses in how network stacks handle TCP connection establishment and state management. The attack mechanism specifically targets the TCP three-way handshake process, where malicious actors flood target systems with connection requests that complete the initial handshake phase but never maintain the actual connection state on the attacker's side. This approach effectively consumes system resources such as memory, file descriptors, and connection tracking tables without actually establishing functional connections that would be useful for legitimate network operations.
The technical flaw underlying CVE-2000-1039 stems from inadequate validation and resource management within TCP/IP stack implementations. When a TCP connection attempt is initiated, the receiving system allocates resources to track the connection state during the handshake process. In vulnerable implementations, these resources remain allocated even after the handshake completes, as the attacker does not proceed with the final connection establishment. This creates a resource exhaustion condition where legitimate connection requests cannot be processed due to the depletion of available connection tracking slots, socket buffers, or memory allocations. The vulnerability operates at a protocol level, making it particularly insidious as it targets the fundamental building blocks of network communication rather than specific application code.
The operational impact of CVE-2000-1039 attacks can be devastating to affected systems and network infrastructure. Targeted servers and network devices may experience complete service unavailability, with legitimate users unable to establish connections while the system remains overwhelmed with pseudo-connections. The resource exhaustion typically manifests as increased system load, reduced response times, and eventual system crashes or restarts. Organizations running web servers, database servers, mail servers, and other network services are particularly vulnerable, as these systems often maintain high connection rates and have limited tolerance for resource exhaustion. The attack can be executed with minimal resources from the attacker side, making it an attractive vector for disrupting critical network services and causing significant business disruption.
Mitigation strategies for CVE-2000-1039 typically involve implementing connection rate limiting, connection tracking timeouts, and resource allocation controls within TCP/IP stacks. Network administrators should configure systems to enforce maximum connection limits, implement aggressive timeout values for incomplete connections, and monitor connection states for unusual patterns. The implementation of SYN cookies, connection tracking limits, and proper resource management in kernel-level TCP implementations provides effective protection against this class of attack. Additionally, deploying network-level firewalls and intrusion detection systems can help identify and block suspicious connection patterns. Organizations should also consider implementing load balancing and redundancy measures to maintain service availability during attacks. This vulnerability aligns with CWE-119, which addresses memory corruption issues, and maps to ATT&CK technique T1498, which covers network denial of service attacks. The broader implications of this vulnerability led to enhanced TCP stack implementations and more robust resource management practices across network infrastructure components, contributing to improved cybersecurity standards in subsequent years.