CVE-2002-0460 in WinSSHD
Summary
by MITRE
Bitvise WinSSHD before 2002-03-16 allows remote attackers to cause a denial of service (resource exhaustion) via a large number of incomplete connections that are not properly terminated, which are not properly freed by SSHd.
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Analysis
by VulDB Data Team • 09/17/2025
The vulnerability identified as CVE-2002-0460 affects Bitvise WinSSHD versions prior to 2002-03-16 and represents a classic resource exhaustion flaw that can lead to denial of service conditions. This vulnerability specifically targets the SSH daemon's handling of incomplete network connections, creating a scenario where remote attackers can systematically consume system resources without proper cleanup mechanisms. The flaw resides in the server's connection management logic where connections that are initiated but never properly terminated remain in memory or system resources, leading to progressive resource depletion over time.
From a technical perspective, this vulnerability demonstrates poor resource management practices within the SSH daemon implementation, where the system fails to properly garbage collect or free resources associated with incomplete connection attempts. The flaw operates by exploiting the connection handling loop to create numerous connection states that persist in the system's memory or connection tables without appropriate cleanup routines. This type of vulnerability aligns with CWE-400, which categorizes resource exhaustion issues in software systems, where attackers can consume available system resources through legitimate but abusive usage patterns.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise system stability and availability. When exploited, the vulnerability allows attackers to consume memory, file descriptors, or other system resources at an accelerated rate, eventually leading to complete service unavailability. This can affect not only the SSH service itself but may also impact other system functions that depend on the exhausted resources. The vulnerability is particularly dangerous in environments where continuous availability is critical, as it can be exploited to maintain persistent denial of service conditions without requiring elevated privileges or complex attack vectors.
Security professionals should note that this vulnerability represents an early example of how connection state management flaws can be weaponized for denial of service attacks, predating many modern defensive mechanisms. The exploitation pattern follows principles outlined in the ATT&CK framework under the T1499 category, which covers resource exhaustion techniques. Organizations should implement connection rate limiting, proper timeout configurations, and regular monitoring of connection states to detect and prevent exploitation. The fix for this vulnerability required proper implementation of connection cleanup routines and resource deallocation mechanisms within the SSH daemon's connection handling code. This remediation approach aligns with secure coding practices that emphasize proper resource management and defensive programming techniques to prevent similar issues in future implementations.