CVE-2006-1952 in TFTP Server
Summary
by MITRE
Directory traversal vulnerability in WinAgents TFTP Server for Windows 3.1 and earlier allows remote attackers to read arbitrary files via "..." (triple dot) sequences in a GET request.
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Analysis
by VulDB Data Team • 09/08/2017
The vulnerability identified as CVE-2006-1952 represents a critical directory traversal flaw within the WinAgents TFTP Server version 3.1 and earlier implementations running on Windows operating systems. This security weakness stems from inadequate input validation mechanisms that fail to properly sanitize file path requests submitted through TFTP GET operations. The specific exploitation technique involves crafting malicious GET requests containing triple dot sequences that bypass normal file system access controls and enable unauthorized file retrieval from the server's file system.
This directory traversal vulnerability operates at the application layer of the network stack and directly violates the principle of least privilege by allowing remote attackers to access files beyond the intended directory boundaries. The flaw exists because the TFTP server implementation does not adequately filter or normalize file path references, permitting attackers to manipulate the file system navigation through sequences like ".." that are typically used to traverse up directory levels. When the server processes these malformed requests, it fails to properly resolve the file paths, resulting in unintended file system access.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with the capability to access sensitive system files, configuration data, and potentially confidential user information stored on the affected server. Attackers can leverage this vulnerability to retrieve critical system files such as password hashes, configuration files containing database credentials, or other sensitive data that could facilitate further compromise of the network infrastructure. The remote nature of the attack means that exploitation can occur from any location without requiring physical access to the system, making it particularly dangerous for network administrators.
From a cybersecurity perspective, this vulnerability aligns with CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal. The attack vector follows patterns consistent with techniques documented in the MITRE ATT&CK framework under the T1083 technique for discovering system information, where adversaries seek to understand the target system's file structure to identify valuable data for exfiltration. The vulnerability demonstrates a fundamental flaw in input validation and access control implementation that has been repeatedly observed across various network services and applications throughout the industry.
Mitigation strategies for this vulnerability require immediate patching of the WinAgents TFTP Server to version 3.2 or later, which contains the necessary fixes for proper path validation. Network administrators should also implement firewall rules to restrict TFTP traffic to only trusted networks and consider disabling TFTP services entirely if they are not essential for business operations. Additional defensive measures include implementing network segmentation to isolate TFTP servers from critical systems, deploying intrusion detection systems to monitor for suspicious TFTP traffic patterns, and conducting regular security assessments to identify other potential path traversal vulnerabilities in similar network services. Organizations should also establish proper access controls and monitoring for TFTP servers to detect unauthorized file access attempts and maintain comprehensive audit logs for forensic analysis.