CVE-2004-2503 in Mail Server
Summary
by MITRE
INweb Mail Server 2.40 allows remote attackers to cause a denial of service (crash) via a large number of connect/disconnect actions to the (1) POP3 and (2) SMTP services.
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Analysis
by VulDB Data Team • 07/19/2017
The vulnerability identified as CVE-2004-2503 affects INweb Mail Server version 2.40 and represents a classic denial of service weakness that exploits the server's handling of connection management protocols. This issue specifically targets the POP3 and SMTP services, which are fundamental components of email infrastructure and critical for business communications. The vulnerability arises from the server's inability to properly manage rapid succession of connection and disconnection events, creating a condition where the service becomes unstable and eventually crashes. The flaw demonstrates poor resource management and inadequate input validation within the connection handling logic, making it susceptible to exploitation through simple but effective traffic patterns that overwhelm the server's connection state tracking mechanisms.
From a technical perspective, this vulnerability operates as a resource exhaustion attack that leverages the server's connection management subsystem. When remote attackers flood the POP3 and SMTP services with numerous connect/disconnect cycles, the server's internal state tracking mechanisms become overwhelmed, leading to memory corruption or thread exhaustion that results in service termination. The attack vector requires minimal sophistication and can be executed using basic network tools to establish and tear down connections rapidly. This type of vulnerability falls under CWE-400, which categorizes resource exhaustion flaws, and specifically relates to the improper handling of connection lifecycle events in network services. The vulnerability demonstrates a lack of proper rate limiting and connection state validation, which are fundamental security controls that should prevent such exploitation scenarios.
The operational impact of CVE-2004-2503 extends beyond simple service disruption to potentially compromise business continuity and email availability for organizations relying on the affected mail server. When the POP3 and SMTP services crash, legitimate users lose access to email retrieval and sending capabilities, creating communication breakdowns that can affect productivity and customer service operations. The vulnerability is particularly concerning because it can be exploited by attackers with minimal technical expertise, making it a popular choice for disruptive attacks. Organizations using INweb Mail Server 2.40 may experience repeated service interruptions, requiring manual intervention to restart services and potentially leading to data loss or email queue corruption. The attack can be executed from any network location without requiring authentication, making it particularly dangerous for publicly accessible mail servers.
Mitigation strategies for this vulnerability should focus on implementing connection rate limiting and proper resource management within the mail server configuration. Network administrators should configure the server to limit the number of connections per client within a given time window, preventing the exploitation of connection state management weaknesses. The implementation of proper logging and monitoring systems can help detect abnormal connection patterns that may indicate attempted exploitation. Additionally, upgrading to a newer version of INweb Mail Server that addresses this specific vulnerability should be prioritized, as the affected version lacks proper defensive mechanisms against connection flooding attacks. From an ATT&CK framework perspective, this vulnerability maps to T1499.004, which covers network denial of service attacks, and demonstrates the importance of implementing proper connection management controls as outlined in the defense-in-depth security principles. Organizations should also consider implementing network-level protections such as firewalls with connection tracking capabilities and intrusion prevention systems that can detect and block excessive connection attempts to prevent exploitation of this vulnerability.