CVE-2002-0405 in Broker FTP Server
Summary
by MITRE
Buffer overflow in Transsoft Broker FTP Server 5.0 evaluation allows remote attackers to cause a denial of service and possibly execute arbitrary code via a CWD command with a large number of . (dot) characters.
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Analysis
by VulDB Data Team • 09/18/2025
The vulnerability identified as CVE-2002-0405 represents a critical buffer overflow flaw within the Transsoft Broker FTP Server version 5.0 evaluation release. This security weakness specifically manifests when processing the CWD (Change Working Directory) command, where an attacker can exploit the server's insufficient input validation mechanisms to craft malicious payloads containing an excessive number of dot characters. The flaw stems from the server's inability to properly handle and sanitize user input, creating a scenario where memory allocation becomes compromised during command processing. The vulnerability operates at the application layer within the FTP protocol implementation, making it particularly dangerous as it can be exploited over network connections without requiring authentication.
The technical implementation of this buffer overflow occurs when the server receives a CWD command with an excessive number of consecutive dot characters, typically exceeding the allocated buffer size within the application's memory structure. This condition creates a classic stack-based buffer overflow scenario where the excess data overflows into adjacent memory regions, potentially corrupting critical program execution elements such as return addresses or function pointers. The flaw aligns with CWE-121, which categorizes stack-based buffer overflow conditions, and demonstrates how inadequate input boundary checking can lead to arbitrary code execution. The vulnerability's exploitation potential extends beyond simple denial of service, as successful exploitation could allow attackers to inject and execute malicious code within the server's execution context, effectively compromising the entire system.
The operational impact of this vulnerability presents significant risks to organizations relying on the Transsoft Broker FTP Server for file transfer operations. Remote attackers can leverage this weakness to either disrupt services through denial of service conditions or escalate privileges to execute unauthorized commands on the affected system. The evaluation version of the software indicates that this vulnerability was present in a released product, suggesting that organizations using the software were exposed to potential compromise without any official patch or mitigation available. This scenario creates a particularly dangerous environment where administrators may not be aware of the vulnerability's existence, especially if they were running the evaluation version without proper security assessments. The attack vector requires only network connectivity to the FTP server, making it accessible to any attacker with basic network reconnaissance capabilities.
Mitigation strategies for this vulnerability must address both immediate defensive measures and long-term remediation approaches. Organizations should implement network segmentation and access controls to limit exposure of the FTP server to untrusted networks, while also considering immediate deployment of vendor patches or updates if available. The implementation of intrusion detection systems can help identify exploitation attempts through monitoring for unusual CWD command patterns containing excessive dot characters. Additionally, security professionals should conduct comprehensive vulnerability assessments to identify all instances of the Transsoft Broker FTP Server within their infrastructure and ensure proper input validation is implemented at the application level. The remediation process should include disabling unnecessary FTP services, implementing proper logging and monitoring of FTP command execution, and establishing network-level restrictions to prevent unauthorized access to the vulnerable server. This vulnerability serves as a critical reminder of the importance of input validation and proper memory management in network services, aligning with ATT&CK technique T1203 for legitimate credential use and T1059 for command and scripting interpreter execution.