CVE-2002-0139 in SpoonFTP
Summary
by MITRE
Pi-Soft SpoonFTP 1.1 and earlier allows remote attackers to redirect traffic to other sites (aka FTP bounce) via the PORT command.
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Analysis
by VulDB Data Team • 09/22/2025
The vulnerability identified as CVE-2002-0139 affects Pi-Soft SpoonFTP version 1.1 and earlier implementations, presenting a significant security risk through improper handling of the FTP PORT command. This flaw enables remote attackers to manipulate network traffic routing by exploiting the FTP protocol's passive connection mechanisms. The vulnerability specifically targets the FTP protocol's ability to establish data connections between client and server, creating an avenue for malicious traffic redirection that can compromise network integrity and user privacy.
The technical implementation of this vulnerability stems from inadequate validation and processing of the PORT command within the FTP server software. When a client sends a PORT command, it specifies the IP address and port number where the server should establish a data connection. In vulnerable versions of SpoonFTP, the system fails to properly validate or sanitize this information, allowing attackers to inject malicious IP addresses and ports. This improper input handling creates a condition where the FTP server will attempt to establish connections to arbitrary destinations specified by the attacker, effectively enabling a form of network traffic redirection. The flaw operates at the protocol level, leveraging the fundamental design of FTP's data connection establishment process to create unintended network behavior.
The operational impact of this vulnerability extends beyond simple traffic redirection, creating potential pathways for more sophisticated attacks within network environments. Attackers can leverage this vulnerability to perform unauthorized network reconnaissance, redirect users to malicious sites, or potentially establish unauthorized communication channels. The vulnerability affects the integrity of network communications by allowing malicious actors to manipulate connection endpoints, potentially leading to man-in-the-middle attacks or data interception. Network administrators face significant challenges in detecting such attacks since the behavior appears legitimate from the FTP protocol perspective, making the vulnerability particularly dangerous in environments where FTP services are commonly used for legitimate file transfers.
This vulnerability aligns with CWE-284, which addresses improper access control in network services, and represents a specific instance of protocol-level manipulation that violates the expected security boundaries of FTP implementations. From an ATT&CK framework perspective, this vulnerability maps to techniques involving network traffic manipulation and protocol manipulation, specifically targeting the execution of malicious network activities through legitimate protocol mechanisms. The attack vector requires minimal privileges and can be executed remotely, making it particularly attractive to threat actors seeking to establish unauthorized network access or redirect traffic for malicious purposes. Organizations should implement immediate mitigations including updating to patched versions of SpoonFTP, implementing network segmentation to limit FTP service exposure, and deploying intrusion detection systems to monitor for anomalous PORT command usage patterns that may indicate exploitation attempts.