CVE-2008-3555 in Links
Summary
by MITRE
Directory traversal vulnerability in index.php in (1) WSN Forum 4.1.43 and earlier, (2) Gallery 4.1.30 and earlier, (3) Knowledge Base (WSNKB) 4.1.36 and earlier, (4) Links 4.1.44 and earlier, and possibly (5) Classifieds before 4.1.30 allows remote attackers to include and execute arbitrary local files via a .. (dot dot) in the TID parameter, as demonstrated by uploading a .jpg file containing PHP sequences.
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Analysis
by VulDB Data Team • 11/03/2024
This directory traversal vulnerability exists in multiple WSN software products including Forum, Gallery, Knowledge Base, and Links versions up to 4.1.43 and earlier. The flaw resides in the index.php script where the TID parameter fails to properly validate user input, allowing attackers to manipulate file paths through directory traversal sequences using the .. (dot dot) notation. The vulnerability specifically affects applications that process user-supplied input without adequate sanitization, creating a path traversal condition that enables arbitrary file inclusion and execution. This represents a classic security weakness where insufficient input validation permits attackers to access files outside the intended directory structure, potentially leading to complete system compromise.
The technical implementation of this vulnerability allows remote attackers to exploit the lack of proper path validation by injecting ../ sequences into the TID parameter. When the application processes this input without proper sanitization, it can traverse directories and include local files that should remain protected. The demonstration case shows attackers uploading malicious .jpg files containing PHP code, which then gets executed when the application processes the file path through the vulnerable parameter. This creates a scenario where attackers can execute arbitrary code on the target system, potentially gaining full control over the affected server. The vulnerability operates at the application layer and can be classified under CWE-22 as Improper Limitation of a Pathname to a Restricted Directory.
The operational impact of this vulnerability is severe and multifaceted, potentially allowing attackers to execute arbitrary code, access sensitive data, and compromise entire systems. Remote attackers can leverage this weakness to upload malicious files, execute shell commands, and gain unauthorized access to the server environment. The vulnerability affects not just individual applications but multiple products within the WSN ecosystem, amplifying the potential attack surface. Attackers can use this weakness to escalate privileges, steal sensitive information, and potentially establish persistent backdoors. The attack can be executed without authentication, making it particularly dangerous as it allows for automated exploitation of vulnerable systems. This vulnerability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter and T1078.004 for Valid Accounts, as it enables attackers to execute commands and potentially maintain access through compromised applications.
Mitigation strategies should focus on implementing proper input validation and sanitization for all user-supplied parameters, particularly those used in file operations. Applications should employ absolute path validation, reject suspicious input patterns, and implement proper access controls to prevent directory traversal attacks. The recommended approach includes implementing whitelisting mechanisms for valid parameters, using secure file handling practices, and ensuring proper input sanitization before processing user data. Additionally, organizations should implement network segmentation, monitor for suspicious file upload activities, and regularly update affected applications to patched versions. The vulnerability highlights the importance of secure coding practices and input validation as fundamental defense mechanisms against path traversal attacks, which should be incorporated into all application development lifecycle processes.