CVE-2007-2639 in TFTPdWin
Summary
by MITRE
Directory traversal vulnerability in TFTPdWin 0.4.2 allows remote attackers to read or modify arbitrary files outside the TFTP root via unspecified vectors.
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Analysis
by VulDB Data Team • 08/31/2018
The directory traversal vulnerability in TFTPdWin 0.4.2 represents a critical security flaw that undermines the fundamental security model of the Trivial File Transfer Protocol implementation. This vulnerability falls under the CWE-22 category, which specifically addresses improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The flaw exists within the TFTP daemon implementation where input validation is insufficient to prevent attackers from manipulating file paths to access files outside the designated TFTP root directory. The vulnerability is particularly concerning because TFTP is traditionally used for simple file transfers in network boot environments and embedded systems, making it a common target for attackers seeking unauthorized access to system resources.
The technical implementation of this vulnerability stems from inadequate input sanitization within the TFTPdWin software, which fails to properly validate or sanitize file paths received from remote clients. Attackers can exploit this weakness by crafting specially formatted TFTP requests that include directory traversal sequences such as "../" or "..\\", allowing them to navigate beyond the intended TFTP root directory and access arbitrary files on the underlying filesystem. This flaw operates at the protocol level where the TFTP client and server exchange file requests without proper authorization checks, enabling unauthorized access to sensitive system files, configuration data, or even executable components that could be modified to compromise system integrity. The unspecified vectors mentioned in the vulnerability description suggest that multiple attack paths exist within the software implementation, making the exploitation more versatile and potentially harder to detect.
The operational impact of this vulnerability extends far beyond simple unauthorized file access, creating significant risks for network security and system integrity. Remote attackers can leverage this vulnerability to read sensitive files such as system configuration data, user credentials stored in configuration files, or even system binaries that could reveal information about the underlying operating system. The ability to modify arbitrary files poses additional risks including the potential for privilege escalation, persistence mechanisms, or the installation of malicious code within the TFTP environment. This vulnerability directly impacts the principle of least privilege and can lead to complete system compromise when combined with other attack vectors, particularly in environments where TFTP is used for network boot processes or firmware updates. The attack surface is broadened because TFTP servers are often deployed in network infrastructure devices, embedded systems, and legacy environments where patch management may be limited.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term security posture improvements. The most effective immediate solution involves upgrading to a patched version of TFTPdWin or migrating to a more secure TFTP implementation that properly validates file paths and implements strict directory restrictions. Network segmentation and firewall rules should be implemented to limit TFTP access to trusted networks and reduce the attack surface. The implementation of network monitoring and intrusion detection systems can help detect anomalous TFTP traffic patterns that might indicate exploitation attempts. Additionally, organizations should conduct comprehensive vulnerability assessments to identify all instances of TFTPdWin or similar vulnerable implementations within their network infrastructure. This vulnerability demonstrates the importance of implementing proper input validation and access controls as outlined in the ATT&CK framework's techniques for privilege escalation and credential access. Regular security audits and penetration testing should be performed to identify similar path traversal vulnerabilities in other network services and applications. The vulnerability also highlights the need for robust software supply chain security practices to ensure that network services are regularly updated and patched against known security flaws.