CVE-2003-0271 in Personal FTP Server
Summary
by MITRE
Buffer overflow in Personal FTP Server allows remote attackers to execute arbitrary code via a long USER argument.
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Analysis
by VulDB Data Team • 05/10/2019
The vulnerability identified as CVE-2003-0271 represents a critical buffer overflow flaw within Personal FTP Server software that exposes systems to remote code execution attacks. This vulnerability specifically affects the authentication handling mechanism of the FTP server where the USER command parameter is processed without adequate bounds checking, creating an exploitable condition that can be leveraged by malicious actors to gain unauthorized control over affected systems. The flaw exists in the server's handling of user credentials during the initial authentication phase, making it particularly dangerous as it can be exploited before legitimate users establish connections.
The technical implementation of this buffer overflow stems from improper input validation within the FTP server's USER command processing routine. When a remote attacker sends a specially crafted USER argument containing excessive data, the server fails to validate the length of the input before copying it into a fixed-size buffer allocated in memory. This classic buffer overflow condition allows the attacker to overwrite adjacent memory locations, potentially including return addresses or function pointers, enabling arbitrary code execution with the privileges of the FTP server process. The vulnerability aligns with CWE-121, which categorizes heap-based buffer overflows, and represents a fundamental flaw in memory management practices within the server application.
From an operational impact perspective, this vulnerability creates significant security risks for organizations relying on Personal FTP Server implementations. Attackers can exploit this condition to execute malicious code remotely without requiring prior authentication, potentially leading to complete system compromise, data exfiltration, or establishment of persistent backdoors. The vulnerability affects the confidentiality, integrity, and availability of the affected systems, as successful exploitation can result in unauthorized access to sensitive data, modification of critical files, or disruption of services. Network security monitoring systems may detect unusual traffic patterns during exploitation attempts, but the initial exploitation often occurs without detection, making it particularly dangerous in environments where traditional security controls are insufficient.
Organizations should implement immediate mitigations including applying vendor patches or updates that address the buffer overflow condition in the FTP server software. System administrators should also consider implementing network segmentation and access controls to limit exposure of FTP services to trusted networks only. Additional defensive measures include monitoring for unusual USER command patterns and implementing intrusion detection systems that can identify potential exploitation attempts. The vulnerability demonstrates the importance of input validation and proper memory management practices in network services, aligning with ATT&CK technique T1190 which covers exploitation of remote services. Regular security assessments and vulnerability scanning should be conducted to identify similar buffer overflow conditions in other network services and applications. Organizations should also consider implementing application whitelisting and privilege separation techniques to minimize the impact of potential exploitation attempts.