CVE-2009-4053 in Home FTP Server
Summary
by MITRE
Multiple directory traversal vulnerabilities in Home FTP Server 1.10.1.139 allow remote authenticated users to (1) create arbitrary directories via directory traversal sequences in an MKD command or (2) create files with any contents in arbitrary directories via directory traversal sequences in a file upload request. NOTE: the provenance of this information is unknown; the details are obtained solely from third party information.
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Analysis
by VulDB Data Team • 11/03/2025
The vulnerability identified as CVE-2009-4053 represents a critical directory traversal flaw in Home FTP Server version 1.10.1.139 that exposes the system to remote authenticated attackers. This vulnerability manifests through two distinct attack vectors that leverage improper input validation in the server's handling of file system operations. The flaw allows authenticated users to manipulate the file system structure and content through carefully crafted directory traversal sequences, effectively bypassing intended access controls and potentially enabling arbitrary file system modifications.
The technical implementation of this vulnerability stems from insufficient validation of user-supplied input in the server's command processing logic. When processing the MKD command for directory creation, the server fails to properly sanitize path traversal sequences such as "../" or similar constructs that would normally be rejected by proper path validation mechanisms. Similarly, during file upload operations, the server does not adequately validate the destination paths specified by clients, allowing attackers to specify arbitrary directory locations. This weakness directly maps to CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as directory traversal or path traversal vulnerabilities. The vulnerability operates at the application layer and can be exploited through the standard ftp protocol, making it particularly dangerous as it requires only basic authentication credentials to be effective.
The operational impact of this vulnerability extends beyond simple unauthorized access to encompass potential system compromise and data exposure. Attackers can leverage the directory traversal capabilities to create malicious directories in system locations, potentially establishing persistent backdoors or hiding malicious files within the file system. The ability to upload files with arbitrary contents to any directory accessible through the FTP interface provides attackers with a mechanism to deploy malware, backdoors, or other malicious payloads directly onto the compromised system. This vulnerability essentially allows attackers to perform arbitrary file system operations that should be restricted to authorized administrators only, creating a significant risk for systems running the vulnerable software. The implications are particularly severe in environments where FTP servers are used for legitimate file sharing or business operations, as unauthorized access to the file system can lead to data theft, system compromise, or service disruption.
Mitigation strategies for this vulnerability should focus on immediate patching of the affected Home FTP Server software to version 1.10.1.140 or later, which contains the necessary fixes for the directory traversal issues. Organizations should implement network segmentation and access control measures to limit FTP server exposure to trusted networks only, reducing the attack surface available to potential attackers. Additionally, the principle of least privilege should be enforced by configuring FTP server accounts with minimal required permissions and restricting access to only necessary directories. Network monitoring solutions should be deployed to detect unusual FTP activity patterns that might indicate exploitation attempts, including unusual directory creation or file upload operations. From an ATT&CK framework perspective, this vulnerability aligns with techniques such as T1078 for valid accounts and T1566 for credential harvesting, as attackers may use legitimate credentials to exploit the vulnerability and gain unauthorized system access. Regular security assessments and vulnerability scanning should be conducted to identify similar issues in other FTP server implementations and ensure comprehensive protection against similar directory traversal attacks.