CVE-2011-4831 in Web File Browser
Summary
by MITRE
Directory traversal vulnerability in webFileBrowser.php in Web File Browser 0.4b14 allows remote authenticated users to read arbitrary files via a ..%2f (encoded dot dot) in the file parameter in a download action.
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Analysis
by VulDB Data Team • 01/24/2025
The vulnerability identified as CVE-2011-4831 represents a critical directory traversal flaw in the Web File Browser 0.4b14 web application. This issue affects the webFileBrowser.php component and specifically targets the file parameter handling during download operations. The vulnerability arises from insufficient input validation and sanitization mechanisms that fail to properly process encoded directory traversal sequences, allowing malicious actors to bypass normal file access restrictions.
This directory traversal vulnerability operates through the exploitation of encoded dot-dot-slash sequences using URL encoding where ..%2f represents the malicious path traversal pattern. When authenticated users submit requests containing this encoded sequence in the file parameter, the web application fails to adequately sanitize the input, enabling attackers to navigate outside the intended directory structure and access arbitrary files on the server. The flaw is particularly concerning because it requires only authenticated access, meaning that any user with valid credentials can exploit this vulnerability to read sensitive files that should normally be restricted.
The technical implementation of this vulnerability stems from improper input validation and path resolution logic within the web application's file handling routines. The application does not effectively filter or decode potentially malicious input sequences, allowing encoded directory traversal attempts to be processed as legitimate file paths. This weakness aligns with CWE-22, which categorizes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The vulnerability demonstrates a classic lack of input sanitization and output encoding practices that are fundamental to secure web application development.
The operational impact of this vulnerability extends beyond simple unauthorized file access, as it can potentially expose sensitive system information including configuration files, database credentials, application source code, and other confidential data. Attackers can leverage this vulnerability to perform reconnaissance activities, gather intelligence about the target system, and potentially escalate privileges within the application environment. The authenticated nature of the exploit means that attackers do not need to perform extensive reconnaissance or social engineering to gain initial access, making this vulnerability particularly dangerous in environments where user accounts are properly managed and controlled.
Organizations affected by this vulnerability should implement immediate mitigations including input validation and sanitization of all file path parameters, implementing proper path normalization techniques, and restricting file access to predefined directories only. The solution involves configuring the web application to reject or properly decode any directory traversal sequences before processing file requests. Security measures should include implementing proper access controls, using whitelist-based file access mechanisms, and ensuring that all user-supplied input undergoes rigorous validation. This vulnerability also highlights the importance of following secure coding practices and implementing proper error handling to prevent information leakage during file access operations, aligning with ATT&CK technique T1566 which addresses credential access through various attack vectors including web application vulnerabilities.
The broader implications of this vulnerability demonstrate the critical importance of input validation in web applications, particularly in file handling components that process user-supplied data. Organizations should conduct comprehensive security assessments of their web applications to identify similar path traversal vulnerabilities and ensure that proper security controls are in place to prevent unauthorized file access. Regular security updates and patch management practices are essential to protect against known vulnerabilities, while proper security training for development teams can help prevent similar issues from being introduced during the software development lifecycle.