CVE-2005-3589 in FileZilla Server Terminal
Summary
by MITRE
Buffer overflow in FileZilla Server Terminal 0.9.4d may allow remote attackers to cause a denial of service (terminal crash) via a long USER ftp command.
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Analysis
by VulDB Data Team • 03/26/2019
The vulnerability identified as CVE-2005-3589 represents a critical buffer overflow flaw within FileZilla Server Terminal version 0.9.4d that specifically targets the handling of USER ftp commands. This issue resides in the server-side implementation where the application fails to properly validate input length before processing user authentication requests, creating a condition where maliciously crafted input can exceed allocated memory buffers. The flaw manifests when a remote attacker sends an excessively long USER command to the FTP server, causing the application to overwrite adjacent memory regions and ultimately leading to application termination.
From a technical perspective, this vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite memory locations beyond the intended buffer boundaries. The vulnerability operates at the protocol level within the FileZilla Server implementation, specifically targeting the authentication subsystem where user credentials are processed. When the server receives a USER command containing more characters than the allocated buffer can accommodate, the excess data overflows into adjacent memory segments, potentially corrupting critical program state information and function return addresses.
The operational impact of this vulnerability extends beyond simple denial of service, as it provides attackers with a mechanism to crash the FileZilla Server Terminal service and potentially disrupt legitimate user access to file transfer capabilities. This vulnerability directly maps to ATT&CK technique T1499.004, which involves network denial of service attacks through service interruption. The remote exploitation capability means that attackers can trigger the vulnerability from any network location without requiring local system access, making it particularly dangerous in production environments where the server may be exposed to untrusted networks.
Mitigation strategies for this vulnerability should focus on immediate patching of the FileZilla Server Terminal software to version 0.9.4e or later, which contains the necessary buffer overflow protections and input validation measures. Additionally, network administrators should implement proper access controls and firewall rules to limit exposure of the FTP service to trusted networks only, while monitoring for unusual USER command patterns that might indicate exploitation attempts. The vulnerability also highlights the importance of input validation and bounds checking in server-side applications, particularly those handling user-provided data through network protocols. Organizations should conduct regular security assessments of their FTP server implementations and ensure that all server components are kept up to date with the latest security patches to prevent similar vulnerabilities from being exploited in their environments.