CVE-2004-0299 in Smallftpd
Summary
by MITRE
Buffer overflow in smallftpd 0.99 allows local users to cause a denial of service (crash) via an FTP request with a large number of "/" (slash) characters.
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Analysis
by VulDB Data Team • 08/10/2025
The vulnerability identified as CVE-2004-0299 represents a classic buffer overflow flaw within the smallftpd 0.99 FTP server implementation that exposes systems to potential denial of service attacks. This issue specifically manifests when the server processes FTP requests containing an excessive number of forward slash characters, creating a condition where the application fails to properly validate input length before attempting to store data in fixed-size memory buffers. The smallftpd server, a lightweight ftp daemon designed for embedded systems and minimal server environments, suffers from inadequate input sanitization mechanisms that allow malicious or malformed requests to overflow memory buffers and subsequently crash the service.
The technical nature of this vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. In this specific case, the buffer overflow occurs during the parsing of FTP commands that contain excessive path separators, causing the application to allocate insufficient memory for processing the request. The flaw operates at the application layer of the network stack, making it particularly dangerous as it can be exploited through standard FTP client connections without requiring special privileges beyond basic network access. The vulnerability demonstrates a fundamental lack of proper input validation and memory management practices that are essential for maintaining system stability and preventing arbitrary code execution or service disruption.
The operational impact of this vulnerability extends beyond simple service interruption to potentially compromise system availability and reliability within environments that depend on the smallftpd service. Local users can exploit this weakness to force the FTP daemon to crash repeatedly, creating a persistent denial of service condition that prevents legitimate users from accessing file transfer services. The exploitability of this vulnerability is relatively straightforward since it only requires sending a specially crafted FTP request containing numerous consecutive forward slashes, making it accessible to attackers with minimal technical expertise. This type of vulnerability is particularly concerning in production environments where FTP services are critical for file management and data exchange operations, as it can effectively render the service unusable and potentially impact business continuity.
Mitigation strategies for CVE-2004-0299 should focus on immediate patching of the smallftpd software to address the buffer overflow condition through proper input validation and bounds checking mechanisms. System administrators should implement network-level restrictions to limit FTP service access and monitor for unusual patterns of FTP requests containing excessive path separators. The implementation of intrusion detection systems can help identify potential exploitation attempts by monitoring for malformed FTP commands that exceed normal request parameters. Additionally, organizations should consider migrating to more robust and actively maintained FTP server implementations that have undergone comprehensive security auditing and contain proper memory management practices. From an att&ck framework perspective, this vulnerability maps to tactic TA0040 (defense evasion) and technique T1499.004 (network disruption) as it enables attackers to disrupt service availability through crafted input manipulation. The vulnerability also demonstrates the importance of secure coding practices and input validation as outlined in the software security development lifecycle, emphasizing that buffer overflow conditions should be prevented through proper bounds checking and memory allocation techniques.