CVE-2002-0406 in Sphereserver
Summary
by MITRE
Menasoft SPHERE server 0.99x and 0.5x allows remote attackers to cause a denial of service by establishing a large number of connections to the server without providing login credentials, which prevents other users from being able to log in.
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Analysis
by VulDB Data Team • 09/18/2025
The Menasoft SPHERE server vulnerability identified as CVE-2002-0406 represents a classic denial of service attack vector that exploits the server's connection handling mechanism. This vulnerability affects versions 0.99x and 0.5x of the SPHERE server software, which was designed as a network authentication server implementing the Secure Remote Password protocol. The flaw stems from the server's inadequate management of unauthenticated connections, creating a scenario where malicious actors can consume server resources through excessive connection attempts without proper authentication.
The technical implementation of this vulnerability demonstrates a fundamental flaw in resource allocation and connection management within the SPHERE server architecture. When remote attackers establish numerous connections to the server without providing valid login credentials, the server maintains these connections in memory and processing queues, effectively consuming available resources. This behavior aligns with CWE-400, which categorizes unchecked resource consumption as a critical weakness in software systems. The server's failure to implement connection rate limiting or resource throttling mechanisms means that legitimate users cannot establish new connections once the resource pool is exhausted, creating a cascading failure that impacts normal service availability.
The operational impact of this vulnerability extends beyond simple service disruption to encompass broader security implications for network infrastructure. Network administrators and system operators face the challenge of maintaining service availability while the server becomes unresponsive to legitimate authentication requests. This vulnerability can be exploited through automated tools that rapidly establish multiple connections, making it particularly dangerous in environments where the server handles critical authentication functions. The attack vector requires minimal technical expertise and can be executed from any network location, making it a preferred method for denial of service attacks against authentication infrastructure.
Mitigation strategies for this vulnerability must address both the immediate resource exhaustion issue and implement long-term architectural improvements. The primary recommendation involves implementing connection rate limiting and maximum connection thresholds to prevent any single client or attack vector from consuming all available resources. System administrators should configure the server to automatically terminate idle connections after a specified timeout period and implement authentication timeouts that prevent prolonged connection holding. This approach aligns with ATT&CK technique T1499.004, which addresses network denial of service attacks through resource exhaustion. Additionally, deploying network-level firewalls and intrusion detection systems can help identify and block suspicious connection patterns before they impact server availability. The vulnerability also underscores the importance of proper input validation and resource management in authentication systems, as outlined in the OWASP Top Ten security principles that emphasize protecting against resource exhaustion attacks through proper connection handling and monitoring mechanisms.