CVE-2001-0345 in Windows
Summary
by MITRE
Microsoft Windows 2000 telnet service allows attackers to prevent idle Telnet sessions from timing out, causing a denial of service by creating a large number of idle sessions.
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Analysis
by VulDB Data Team • 05/21/2019
The vulnerability described in CVE-2001-0345 represents a significant denial of service weakness within Microsoft Windows 2000 telnet service implementation. This flaw specifically targets the session management mechanism of the telnet protocol service, allowing malicious actors to exploit idle session handling behaviors. The vulnerability operates by enabling attackers to maintain numerous idle telnet connections without proper timeout enforcement, effectively consuming system resources and rendering legitimate users unable to establish new connections.
This security weakness stems from improper handling of idle session timeouts within the Windows 2000 telnet service architecture. The flaw allows attackers to create multiple telnet connections that remain active in an idle state, bypassing normal session expiration mechanisms that should automatically terminate inactive connections. The root cause lies in the service's failure to properly validate or manage connection states when sessions remain inactive for extended periods. This issue directly relates to CWE-400, which categorizes unchecked resource consumption as a fundamental weakness in resource management, and specifically aligns with CWE-1321 which addresses improper handling of connection states in network services.
The operational impact of this vulnerability extends beyond simple service disruption to create substantial system resource exhaustion. When attackers maintain numerous idle sessions, they consume memory, file descriptors, and other system resources that should be available for legitimate users. The telnet service on Windows 2000 systems can become overwhelmed with these persistent idle connections, leading to complete denial of service for authorized users attempting to establish new telnet sessions. This attack vector is particularly dangerous because it requires minimal privileges and can be executed from remote locations, making it an attractive target for network adversaries seeking to disrupt service availability.
From an adversarial perspective, this vulnerability enables attackers to execute sophisticated denial of service campaigns against Windows 2000 systems without requiring complex exploitation techniques. The attack methodology involves establishing multiple telnet connections and maintaining them in idle states, which can be automated using simple scripts or tools. The effectiveness of this attack is amplified by the fact that Windows 2000 telnet service does not implement proper resource limiting or connection monitoring to detect and terminate abusive idle session patterns. This vulnerability also maps to ATT&CK technique T1499.004 which covers network denial of service attacks and demonstrates how basic protocol implementation flaws can create significant security impact.
Mitigation strategies for CVE-2001-0345 should focus on both immediate defensive measures and long-term architectural improvements. System administrators should implement connection limiting mechanisms that restrict the number of simultaneous telnet sessions per user or system-wide. Network-level controls including firewall rules and rate limiting can help prevent excessive connection attempts from single sources. The most effective remediation involves upgrading to modern operating systems that properly implement session timeout mechanisms and resource management. Additionally, implementing monitoring systems to detect unusual connection patterns and automated alerts for excessive idle sessions can provide early warning of potential exploitation attempts. Organizations should also consider disabling telnet services entirely in favor of more secure remote access protocols such as ssh, which provide better resource management and security features. The vulnerability highlights the critical importance of proper resource management in network services and demonstrates how seemingly simple protocol implementations can create significant security weaknesses when not properly secured.