CVE-2004-0252 in FTP Server
Summary
by MITRE
TYPSoft FTP Server 1.10 allows remote attackers to cause a denial of service (CPU consumption) via an empty USER name.
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Analysis
by VulDB Data Team • 07/13/2025
The vulnerability identified as CVE-2004-0252 affects TYPSoft FTP Server version 1.10 and represents a classic denial of service flaw that exploits improper input validation mechanisms within the FTP protocol implementation. This issue specifically targets the USER command handling within the FTP server software, where an empty username parameter triggers abnormal processing behavior that consumes excessive system resources. The vulnerability stems from the server's failure to properly validate and sanitize authentication input before processing, creating a condition where malformed or empty credentials can be submitted without proper error handling.
From a technical perspective, the flaw manifests when a remote attacker sends an FTP USER command with an empty username field, typically formatted as USER followed by a carriage return and line feed sequence without any subsequent username data. The TYPSoft FTP Server 1.10 implementation processes this malformed input by entering an infinite loop or consuming excessive CPU cycles during authentication attempt validation, effectively causing the server to become unresponsive to legitimate client connections. This behavior aligns with CWE-400, which categorizes unchecked resource consumption as a vulnerability where applications fail to properly handle resource allocation and deallocation, leading to system instability and service disruption.
The operational impact of this vulnerability extends beyond simple service interruption, as it can be exploited by malicious actors to launch resource exhaustion attacks against FTP servers running the affected software. Attackers can repeatedly send empty USER commands to consume CPU cycles continuously, potentially leading to system crashes or making the server unavailable to legitimate users. The vulnerability is particularly concerning because it requires minimal effort to exploit and can be automated, making it an attractive target for denial of service attacks. This type of attack pattern is consistent with techniques described in the MITRE ATT&CK framework under the T1499 category for network denial of service attacks, where adversaries seek to disrupt services through resource exhaustion.
The security implications of CVE-2004-0252 highlight the importance of proper input validation and error handling in network services, particularly those handling authentication protocols. The vulnerability demonstrates how basic protocol implementation flaws can create significant security risks when servers fail to validate user input before processing. Organizations running TYPSoft FTP Server 1.10 should immediately implement mitigations including updating to patched versions of the software, implementing firewall rules to limit FTP access, and monitoring for unusual authentication patterns. The flaw also underscores the need for comprehensive testing of authentication mechanisms and proper resource management practices to prevent similar issues in other network services. Additionally, this vulnerability serves as a reminder that even legacy FTP implementations can contain critical security flaws that require immediate attention to maintain system integrity and availability.