CVE-2003-0203 in moxftp
Summary
by MITRE
Buffer overflow in moxftp 2.2 and earlier allows remote malicious FTP servers to execute arbitrary code via a long FTP banner.
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Analysis
by VulDB Data Team • 12/07/2024
The vulnerability identified as CVE-2003-0203 represents a critical buffer overflow flaw affecting moxftp version 2.2 and earlier implementations. This security weakness resides within the FTP client software's handling of server responses, specifically the FTP banner message that servers send upon connection. The flaw occurs when the client receives an excessively long banner string from a malicious FTP server, causing the application to overwrite adjacent memory locations beyond the allocated buffer boundaries. Such buffer overflow conditions create predictable memory corruption patterns that can be exploited by attackers to inject and execute arbitrary code on the victim's system. The vulnerability is classified as a remote code execution flaw because it does not require local system access or user interaction to exploit, making it particularly dangerous in networked environments where users might connect to untrusted FTP servers.
The technical implementation of this vulnerability stems from improper input validation within the FTP client's banner processing routine. When moxftp establishes a connection to an FTP server, it expects to receive a standard banner message containing server identification information. However, the software fails to implement adequate bounds checking or string length validation before copying the banner data into a fixed-size buffer. This classic buffer overflow scenario aligns with CWE-121, which describes stack-based buffer overflow conditions, and potentially CWE-787, which covers out-of-bounds write vulnerabilities. The flaw essentially allows an attacker to control the program flow by overwriting return addresses or other critical memory segments, enabling arbitrary code execution with the privileges of the affected user.
The operational impact of CVE-2003-0203 extends beyond simple remote code execution to encompass potential system compromise and data exposure. When successfully exploited, the vulnerability allows attackers to execute malicious code on vulnerable systems, potentially leading to complete system takeover, data theft, or deployment of additional malware. The attack vector is particularly concerning because it requires minimal user interaction beyond connecting to a malicious FTP server, making it suitable for automated exploitation campaigns. This vulnerability affects organizations using outdated moxftp implementations and highlights the importance of maintaining current software versions. The flaw also demonstrates the broader risks associated with legacy FTP client software that may not receive security updates or patches, creating persistent attack surfaces within enterprise networks.
Mitigation strategies for CVE-2003-0203 focus on immediate remediation and long-term security hardening measures. The primary solution involves upgrading to moxftp versions that contain proper input validation and buffer overflow protections, typically versions 2.3 or later. Organizations should also implement network segmentation and firewall rules to restrict FTP server access, particularly to systems running vulnerable software. Additional protective measures include disabling unnecessary FTP client functionality, implementing network monitoring to detect suspicious banner responses, and conducting regular security assessments of networked applications. From an ATT&CK framework perspective, this vulnerability maps to techniques involving remote code execution through network protocols and privilege escalation through software exploitation. System administrators should also consider implementing intrusion detection systems to monitor for exploitation attempts and establish incident response procedures for handling potential compromise scenarios. Regular vulnerability scanning and patch management programs are essential to prevent similar issues from arising in other legacy applications.