CVE-2002-1433 in Mailserver
Summary
by MITRE
Kerio MailServer 5.0 allows remote attackers to cause a denial of service (hang) via SYN packets to the supported network services.
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Analysis
by VulDB Data Team • 06/13/2018
The vulnerability identified as CVE-2002-1433 affects Kerio MailServer version 5.0, representing a significant security flaw that enables remote attackers to disrupt service availability through crafted network traffic. This issue manifests as a denial of service condition where the mail server becomes unresponsive or hangs when processing specific SYN packets directed at its supported network services. The vulnerability exploits fundamental aspects of network protocol handling within the mail server implementation, demonstrating a critical weakness in the server's ability to manage incoming connection requests properly. Such a flaw represents a classic network-level attack vector that can severely impact organizational communication infrastructure and business continuity operations.
The technical implementation of this vulnerability stems from inadequate handling of SYN packets within the Kerio MailServer's network stack processing. When the server receives malformed or specially crafted SYN packets, it fails to properly process these connection initiation requests, leading to resource exhaustion or state machine corruption that results in the server hanging. This behavior aligns with CWE-119, which addresses memory safety issues, and specifically relates to improper handling of network protocol states. The vulnerability essentially creates a condition where legitimate network services become unavailable due to the server's inability to process or reject malicious connection attempts properly. From an attack perspective, this represents a straightforward denial of service scenario that requires minimal technical expertise to execute, making it particularly dangerous for organizations relying on the affected mail server platform.
The operational impact of CVE-2002-1433 extends beyond simple service disruption to potentially compromise business operations and communication workflows. Organizations utilizing Kerio MailServer 5.0 may experience complete service unavailability during attack periods, affecting email delivery, user access to mail services, and overall productivity. The hanging state of the server creates a cascading effect on dependent services and can impact backup systems or failover mechanisms that rely on the mail server's availability. From a security posture perspective, this vulnerability enables attackers to perform low-cost disruption attacks that can be executed from remote locations without requiring significant privileges or specialized tools. The vulnerability also exposes weaknesses in the server's robustness and resilience against network-level attacks, indicating broader architectural concerns that may affect other aspects of the system's security.
Mitigation strategies for CVE-2002-1433 should focus on both immediate defensive measures and long-term architectural improvements. Network-level protections including firewall rules and intrusion prevention systems can help filter malicious SYN packets before they reach the mail server, utilizing techniques such as SYN cookies or connection rate limiting to prevent the attack from succeeding. Organizations should implement proper network segmentation to isolate critical mail services and reduce the attack surface available to potential adversaries. The most effective long-term solution involves upgrading to a patched version of Kerio MailServer that properly handles SYN packet processing and implements robust error handling for malformed network traffic. Additionally, implementing monitoring and alerting systems that can detect unusual connection patterns or service hanging behaviors provides early warning capabilities for potential exploitation attempts, aligning with ATT&CK technique T1499 which covers network denial of service attacks. Regular security assessments and vulnerability scanning should be conducted to identify similar weaknesses in network services and ensure comprehensive protection against similar attack vectors.