CVE-2002-2026 in BrowseFTP
Summary
by MITRE
Buffer overflow in BrowseFTP 1.62 client allows remote FTP servers to execute arbitrary code via a long FTP "220" message reply.
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Analysis
by VulDB Data Team • 05/29/2025
The vulnerability identified as CVE-2002-2026 represents a critical buffer overflow flaw in the BrowseFTP 1.62 client software that exposes users to remote code execution risks. This vulnerability specifically targets the client's handling of FTP server responses, particularly the initial greeting message that servers send upon connection. The FTP protocol uses a standardized reply code system where the "220" code indicates that the server is ready to accept connections and is typically accompanied by a welcome message that can contain various informational text. The BrowseFTP client fails to properly validate the length of this initial response message, creating a condition where an attacker-controlled FTP server can craft a malicious response containing excessive data that exceeds the client's allocated buffer space.
The technical implementation of this vulnerability stems from inadequate input validation within the client's FTP protocol parsing logic. When the BrowseFTP client establishes a connection to an FTP server, it expects the server to respond with a standard greeting message that includes the 220 reply code followed by a brief introductory message. However, the client's buffer management does not enforce strict length limits on this response, allowing an attacker to send a specially crafted reply containing thousands of bytes of data. This overflow condition occurs because the client allocates a fixed-size buffer to store the server's response, and when the actual response exceeds this predetermined limit, the excess data overwrites adjacent memory locations. This memory corruption can lead to unpredictable behavior including application crashes, stack corruption, or more critically, the execution of arbitrary code within the context of the user running the BrowseFTP client.
The operational impact of this vulnerability extends beyond simple application instability, presenting a significant security risk that can be exploited by remote attackers without requiring any user interaction or authentication. An attacker who controls an FTP server can leverage this vulnerability to execute malicious code on any system running the vulnerable BrowseFTP client, potentially gaining full control of the victim's machine. This makes the vulnerability particularly dangerous in environments where users might connect to untrusted FTP servers, such as public FTP services, or when users download files from potentially compromised servers. The exploitability of this vulnerability is enhanced by the fact that the attack requires no special privileges or user consent, making it a highly attractive target for automated exploitation tools. The vulnerability directly maps to CWE-121, which describes heap-based buffer overflow conditions, and can be categorized under ATT&CK technique T1190 for Exploit Public-Facing Application, as it allows attackers to compromise systems through network-based attacks against vulnerable client applications.
Mitigation strategies for this vulnerability require immediate action from affected organizations and users. The primary and most effective solution involves updating to a patched version of BrowseFTP that properly validates input lengths and implements robust buffer management techniques. System administrators should prioritize updating all instances of the vulnerable software across their network infrastructure, particularly in environments where users may connect to untrusted FTP servers. Network segmentation and access controls can provide additional defense-in-depth measures, limiting the potential impact of successful exploitation attempts. Organizations should also implement monitoring for suspicious FTP traffic patterns that might indicate exploitation attempts, and consider deploying intrusion detection systems that can identify malformed FTP responses. The vulnerability highlights the importance of proper input validation and memory management practices in network protocol implementations, reinforcing the need for secure coding standards and regular security assessments of client applications that handle network communications. Users should be educated about the risks of connecting to untrusted FTP servers and the importance of keeping their software updated to protect against known vulnerabilities.