CVE-2015-3306 in ProFTPD
Summary
by MITRE
The mod_copy module in ProFTPD 1.3.5 allows remote attackers to read and write to arbitrary files via the site cpfr and site cpto commands.
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Analysis
by VulDB Data Team • 11/29/2024
The mod_copy module in ProFTPD version 1.3.5 contains a critical vulnerability that enables remote attackers to perform unauthorized file operations through specifically crafted FTP commands. This vulnerability specifically affects the site cpfr and site cpto commands which are designed to facilitate file copying operations within the FTP server. The flaw represents a classic path traversal and privilege escalation issue that fundamentally compromises the integrity and confidentiality of the file system. The vulnerability exists due to insufficient input validation and sanitization within the module's command processing logic, allowing attackers to manipulate file paths and bypass normal access controls.
The technical exploitation of this vulnerability relies on the attacker's ability to craft malicious FTP commands that manipulate the source and destination file paths through the cpfr (copy from) and cpto (copy to) commands. When these commands are processed by the vulnerable mod_copy module, the server fails to properly validate or sanitize the file paths, enabling attackers to specify arbitrary file locations on the server's file system. This allows for both read and write operations to occur against files outside the normal FTP user's designated directories, effectively breaking the isolation that should exist between different users and system resources. The vulnerability essentially allows an attacker to copy files from any location on the server to any other location, potentially enabling data exfiltration, system compromise, or privilege escalation attacks.
The operational impact of this vulnerability is severe and multifaceted, affecting both data confidentiality and system integrity. Attackers can leverage this vulnerability to access sensitive files including configuration files, user data, system logs, and potentially even system binaries. The ability to write arbitrary files opens the door to more sophisticated attacks such as planting backdoors, modifying system files, or creating malicious scripts that persist across system reboots. This vulnerability particularly affects organizations that rely on ProFTPD for file transfer services and have not implemented proper security measures or updates. The impact extends beyond immediate data loss to include potential system compromise and compliance violations, as unauthorized access to system files may violate various regulatory requirements.
Mitigation strategies for this vulnerability should include immediate patching of the ProFTPD server to version 1.3.5a or later, which contains the necessary fixes for the mod_copy module. Organizations should also implement network segmentation to limit access to FTP services and consider disabling the mod_copy module entirely if copy functionality is not required. Additional security measures include implementing proper input validation on all FTP commands, using firewall rules to restrict FTP access to trusted networks, and monitoring FTP logs for suspicious cpfr and cpto command usage. This vulnerability aligns with CWE-22 Path Traversal and CWE-73 Improper Neutralization of Special Elements in Output Used by a Downstream Component, and maps to ATT&CK techniques including T1078 Valid Accounts for persistent access and T1566 Phishing for credential theft. System administrators should also consider implementing intrusion detection systems to monitor for exploitation attempts and maintain regular backups to ensure recovery capability in case of successful compromise.