CVE-2000-0831 in FTP++ Server
Summary
by MITRE
Buffer overflow in Fastream FTP++ 2.0 allows remote attackers to cause a denial of service and possibly execute arbitrary commands via a long username.
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Analysis
by VulDB Data Team • 04/06/2019
The vulnerability identified as CVE-2000-0831 represents a critical buffer overflow flaw in Fastream FTP++ version 2.0 that exposes systems to remote exploitation. This issue stems from inadequate input validation within the FTP server implementation where user-provided username data is processed without proper bounds checking. The flaw manifests when an attacker submits a specially crafted username string that exceeds the allocated buffer space, causing memory corruption that can lead to unpredictable system behavior.
This buffer overflow vulnerability operates at the application layer and specifically targets the authentication mechanism of the FTP service. The technical implementation fails to enforce maximum length restrictions on username inputs, allowing malicious actors to overwrite adjacent memory locations in the program's execution space. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, which occurs when data is written beyond the bounds of a fixed-length buffer allocated on the stack. Such memory corruption can result in program termination, stack corruption, or in more severe cases, arbitrary code execution.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enable remote code execution, making it particularly dangerous for systems that rely on FTP services for file transfers and remote access. When exploited successfully, attackers can leverage the buffer overflow to inject and execute malicious code with the privileges of the FTP service process, potentially leading to complete system compromise. The vulnerability affects systems running Fastream FTP++ 2.0 where the service is accessible over the network, creating an attack surface that can be exploited by remote adversaries without requiring local access or authentication.
From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1190 for exploiting vulnerabilities in remote services, and T1059 for executing commands through compromised services. The attack vector requires network connectivity to the affected FTP service and can be automated through various exploitation frameworks. The vulnerability demonstrates poor defensive programming practices and highlights the importance of input validation and memory safety in network-facing applications. Organizations should prioritize patching this vulnerability immediately and implement network segmentation to limit exposure. Additionally, monitoring for unusual authentication patterns and implementing intrusion detection systems can help identify exploitation attempts. The remediation strategy should include upgrading to a patched version of Fastream FTP++, implementing proper input length validation, and conducting security reviews of all network services to identify similar buffer overflow vulnerabilities in the codebase.