CVE-2003-0477 in wzdftpd
Summary
by MITRE
wzdftpd 0.1rc4 and earlier allows remote attackers to cause a denial of service (crash) via a PORT command without an argument.
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Analysis
by VulDB Data Team • 06/14/2018
The vulnerability identified as CVE-2003-0477 affects wzdftpd version 0.1rc4 and earlier implementations, representing a critical denial of service flaw that can be exploited by remote attackers to crash the affected FTP server. This vulnerability specifically targets the handling of PORT commands within the FTP protocol implementation, where the server fails to properly validate or process incoming PORT commands that lack required arguments. The flaw demonstrates a classic buffer over-read or improper input validation issue that occurs when the server attempts to parse FTP commands without adequate parameter checking.
The technical execution of this vulnerability involves sending a malformed PORT command to the wzdftpd server where the command is issued without any arguments. When the server processes this command, it attempts to parse the command structure expecting specific parameters that are absent, leading to an unhandled exception or memory access violation. This type of vulnerability falls under CWE-129, which encompasses improper validation of the length or size of input data, and can be categorized as a form of input validation error within the context of network protocol implementations. The attack vector is particularly dangerous because it requires no authentication and can be executed from any remote location capable of establishing an FTP connection to the vulnerable server.
From an operational impact perspective, this vulnerability creates significant risk for organizations relying on wzdftpd as their primary FTP server implementation. The denial of service condition results in complete service interruption, preventing legitimate users from accessing file transfer capabilities and potentially causing business disruption. The crash typically affects the entire FTP service, requiring manual intervention to restart the server process and restore normal operations. This vulnerability can be exploited by automated scanning tools or malicious actors seeking to disrupt services, making it particularly dangerous in environments where continuous availability is critical. The impact extends beyond simple service interruption as it can affect backup operations, automated file transfers, and any system relying on FTP connectivity for data exchange.
Mitigation strategies for this vulnerability should include immediate patching of affected wzdftpd installations to version 0.1rc5 or later, which contains the necessary fixes for proper PORT command argument validation. Organizations should also implement network-level protections such as firewall rules that restrict FTP access to trusted networks or implement intrusion detection systems that can identify and block malformed PORT commands. Additionally, the use of alternative FTP server implementations such as vsftpd, ProFTPD, or other modern FTP daemons that have undergone more rigorous security review processes is recommended. The vulnerability also highlights the importance of implementing proper input validation and error handling in network services, aligning with ATT&CK technique T1499.004 for network denial of service attacks. Organizations should also consider implementing monitoring solutions that can detect service crashes or restarts that may indicate exploitation attempts, as well as maintaining regular security assessments of all network services to identify similar vulnerabilities in other software components.