CVE-2000-0943 in bftpd
Summary
by MITRE
Buffer overflow in bftp daemon (bftpd) 1.0.11 allows remote attackers to cause a denial of service and possibly execute arbitrary commands via a long USER command.
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Analysis
by VulDB Data Team • 10/12/2025
The CVE-2000-0943 vulnerability represents a critical buffer overflow flaw in the bftp daemon version 1.0.11 which operates as a lightweight ftp server implementation. This vulnerability specifically affects the user authentication handling mechanism where the daemon fails to properly validate input length during the USER command processing phase. The bftpd daemon, designed for minimal resource consumption and simplicity, becomes susceptible to exploitation when remote attackers send maliciously crafted USER commands containing excessive data beyond the allocated buffer space. This particular implementation flaw demonstrates a classic security weakness where insufficient bounds checking allows memory corruption to occur during command parsing operations.
The technical exploitation of this buffer overflow vulnerability occurs when an attacker sends a USER command with data exceeding the predefined buffer capacity within the daemon's memory structure. When the bftpd daemon processes this malformed input, it writes beyond the allocated memory boundaries, potentially overwriting adjacent memory locations including return addresses and control data. This memory corruption can result in immediate daemon termination leading to denial of service conditions or, in more sophisticated exploitation scenarios, could allow attackers to inject and execute arbitrary code within the daemon's execution context. The vulnerability directly maps to CWE-121 which describes heap-based buffer overflow conditions and CWE-787 which addresses out-of-bounds write vulnerabilities.
Operationally this vulnerability presents significant risks to systems running the affected bftpd daemon version as it can be exploited remotely without requiring authentication credentials. The denial of service impact is immediate and straightforward where attackers can simply send a specially crafted USER command to crash the ftp daemon service, rendering the ftp functionality unavailable to legitimate users. However, the potential for remote code execution adds a more severe dimension to the threat model, as successful exploitation could allow attackers to gain unauthorized access to the system with the privileges of the ftp daemon process. This vulnerability particularly affects environments where ftp services are exposed to untrusted networks or where the daemon runs with elevated privileges, creating potential escalation paths for attackers seeking system compromise.
Mitigation strategies for CVE-2000-0943 should prioritize immediate patching of the bftpd daemon to version 1.0.12 or later which contains the necessary buffer overflow protections. System administrators should implement network segmentation to limit exposure of ftp services to trusted networks only, while also considering the deployment of intrusion detection systems to monitor for suspicious USER command patterns. Additional protective measures include implementing strict input validation on ftp traffic, configuring firewalls to limit ftp service access, and monitoring for abnormal daemon behavior or service interruptions. From an ATT&CK framework perspective, this vulnerability aligns with techniques involving remote code execution and privilege escalation, making it particularly concerning for defenders who must protect against both service disruption and potential system compromise. Organizations should also conduct thorough vulnerability assessments to identify all instances of the affected bftpd version and ensure comprehensive patch management processes are in place to prevent similar issues in other software components.