CVE-2001-0450 in Broker FTP Server
Summary
by MITRE
Directory traversal vulnerability in Transsoft FTP Broker before 5.5 allows attackers to (1) delete arbitrary files via DELETE, or (2) list arbitrary directories via LIST, via a .. (dot dot) in the file name.
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Analysis
by VulDB Data Team • 05/11/2019
The vulnerability identified as CVE-2001-0450 represents a critical directory traversal flaw within the Transsoft FTP Broker software version 5.4 and earlier. This security weakness stems from insufficient input validation mechanisms that fail to properly sanitize user-supplied file paths during FTP operations. The vulnerability specifically affects two primary FTP commands: DELETE and LIST, both of which are fundamental operations in file transfer protocols. When an attacker crafts malicious file paths containing .. (dot dot) sequences, the system fails to properly resolve these references, allowing unauthorized access to directories outside the intended scope.
The technical implementation of this vulnerability resides in the software's path resolution algorithm which does not adequately validate or sanitize file path components before processing FTP commands. This flaw aligns with CWE-22, which specifically addresses Improper Limitation of a Pathname to a Restricted Directory, commonly known as Path Traversal. The vulnerability enables attackers to manipulate the file system through crafted FTP requests, bypassing normal access controls that should restrict file operations to specific directories. The root cause lies in the absence of proper path normalization and validation routines that would typically strip or reject directory traversal sequences from user inputs.
Operationally, this vulnerability presents significant risks to organizations relying on Transsoft FTP Broker for file management and data transfer operations. An attacker with access to the FTP service can exploit this weakness to delete critical system files, potentially causing system instability or complete service disruption. The LIST command vulnerability allows attackers to enumerate directories beyond their authorized scope, enabling reconnaissance activities that could lead to further exploitation. This weakness directly impacts the confidentiality, integrity, and availability of the affected system, making it a serious concern for enterprise environments where file system access controls are paramount. The vulnerability can be exploited remotely without requiring authentication for certain operations, amplifying its potential impact.
Mitigation strategies for this vulnerability primarily involve immediate software updates to Transsoft FTP Broker version 5.5 or later, which contain patches addressing the directory traversal issue. Organizations should also implement network segmentation to limit access to FTP services and deploy firewall rules that restrict FTP traffic to authorized users and systems. Input validation should be strengthened at all levels of the application stack, with explicit checks for directory traversal sequences in file paths. Additionally, implementing principle of least privilege access controls and regular security audits can help reduce the attack surface. From a defensive perspective, this vulnerability demonstrates the importance of proper input validation and path handling, aligning with ATT&CK technique T1078 for Valid Accounts and T1566 for Phishing as attackers may leverage such weaknesses to establish persistent access or escalate privileges within compromised systems.