CVE-2002-2237 in TFTP Server
Summary
by MITRE
tftp32 TFTP server 2.21 and earlier allows remote attackers to cause a denial of service via a GET request with a DOS device name such as com1 or aux.
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Analysis
by VulDB Data Team • 11/25/2024
The vulnerability identified as CVE-2002-2237 affects tftp32 TFTP server version 2.21 and earlier implementations, presenting a significant denial of service risk to network infrastructure. This flaw specifically manifests when the server processes GET requests containing DOS device names such as com1 or aux, which are legacy Windows operating system device identifiers that should not be accessible through network protocols. The vulnerability stems from inadequate input validation within the TFTP server's file access handling mechanism, where the system fails to properly sanitize or reject requests containing these special device names that could potentially lead to system resource exhaustion or process interruption.
From a technical perspective, this vulnerability represents a classic case of improper input validation and inadequate security controls in network services. The tftp32 server implementation does not adequately filter or reject requests that reference DOS device names, which are typically reserved system identifiers in Windows environments. When processing a GET request with such device names, the server attempts to handle these invalid references in a manner that causes system resources to become unavailable or processes to terminate unexpectedly. This behavior aligns with CWE-20, which describes improper input validation, and demonstrates how legacy operating system concepts can create security weaknesses in network services when not properly accounted for in modern implementations.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be exploited by remote attackers to systematically deny access to legitimate users. Attackers can leverage this weakness by sending specially crafted GET requests containing DOS device names, causing the TFTP server to consume excessive resources or crash entirely. This denial of service condition affects network administrators who rely on TFTP services for configuration management, firmware updates, and other critical network operations. The vulnerability particularly impacts environments where TFTP servers are used for automated network device management, as such attacks can render network infrastructure inaccessible and potentially compromise network availability. Organizations using tftp32 servers in production environments face significant risk of service interruption, especially in mission-critical scenarios where network availability is paramount.
Mitigation strategies for this vulnerability primarily focus on immediate software updates and input validation enhancements. The most effective solution involves upgrading to tftp32 server versions beyond 2.21, where the developers have implemented proper input sanitization for device names and file access requests. Network administrators should also implement firewall rules and access control lists to restrict TFTP server access to trusted networks only, reducing the attack surface available to potential remote attackers. Additionally, implementing monitoring solutions to detect unusual GET request patterns containing device names can help identify exploitation attempts. From an ATT&CK framework perspective, this vulnerability maps to T1499.004, which covers network denial of service attacks, and T1566.002, covering spearphishing attachments, as attackers may use this vulnerability as part of broader attack campaigns. Organizations should also consider implementing network segmentation and limiting TFTP server functionality to only necessary operations while maintaining proper logging and audit trails to detect and respond to potential exploitation attempts effectively.