CVE-2004-2037 in Lightweight FTP Server
Summary
by MITRE
Buffer overflow in Mollensoft Lightweight FTP Server 3.6 allows remote authenticated users to cause a denial of service (crash) and possibly execute arbitrary code via a long CWD command, as demonstrated in one example by using the "cd" command in an interactive FTP client.
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Analysis
by VulDB Data Team • 07/31/2025
The CVE-2004-2037 vulnerability represents a critical buffer overflow flaw in Mollensoft Lightweight FTP Server version 3.6 that exposes remote authenticated users to significant security risks. This vulnerability specifically manifests when the server processes a Command Working Directory (CWD) command with excessively long input parameters, creating a condition where memory allocation exceeds intended boundaries. The flaw operates at the protocol level within the FTP server implementation, making it particularly dangerous as it can be exploited by legitimate authenticated users who have already established connections to the system.
The technical implementation of this vulnerability stems from inadequate input validation within the CWD command handler of the FTP server software. When a remote authenticated user submits a CWD command containing more data than the allocated buffer can accommodate, the excess data overflows into adjacent memory regions, potentially corrupting critical program structures or even allowing code execution. This type of buffer overflow vulnerability aligns with CWE-121, which categorizes buffer overflow conditions where insufficient bounds checking allows attackers to overwrite memory locations. The vulnerability's exploitation path demonstrates how authenticated access can be leveraged to escalate privileges and compromise system integrity.
The operational impact of CVE-2004-2037 extends beyond simple denial of service conditions to potentially enable arbitrary code execution within the server environment. While the vulnerability initially manifests as a crash that terminates the FTP service, the underlying memory corruption can be manipulated to redirect program execution flow, allowing attackers to inject and execute malicious code with the privileges of the FTP server process. This represents a significant threat to system availability and data integrity, as attackers can not only disrupt services but also establish persistent access points within the network infrastructure. The vulnerability's classification under the ATT&CK framework would align with T1071.004 for application layer protocol manipulation and T1499.004 for network disruption, highlighting both the service availability and potential persistence aspects of the flaw.
Mitigation strategies for this vulnerability should prioritize immediate patching of the Mollensoft Lightweight FTP Server to version 3.7 or later, which includes proper input validation and buffer management. System administrators should implement network segmentation to limit access to FTP services and deploy intrusion detection systems to monitor for unusual CWD command patterns. Additionally, enforcing strict authentication controls and implementing regular security audits of FTP server configurations can help reduce the attack surface. The vulnerability underscores the importance of proper input validation and memory management practices in network service implementations, particularly in protocols where authenticated users can submit arbitrary commands to server processes. Organizations should also consider migrating to more modern FTP implementations or alternative secure file transfer protocols that have better security track records and more robust memory management practices.