Directory Traversal, also known as Path Traversal or Directory Climbing, is a type of security vulnerability that occurs when an attacker can access files or directories outside of the intended directory structure on a web server or file system. Attackers exploit this vulnerability to access sensitive files, execute unauthorized commands, or compromise the security of a system.
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File System Navigation: Web servers and applications often allow users to access files or resources by specifying a file path or URL.
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Input Manipulation: Attackers manipulate input parameters, such as file paths or URLs, by adding special characters or sequences to navigate to directories outside of the intended scope.
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Traversal Attack: By exploiting insufficient input validation or sanitization, attackers traverse directories, accessing files or directories containing sensitive information or executable code.
Suppose a web application serves files based on user-supplied file paths, such as example.com/files?path=user_input. An attacker may manipulate the input parameter to access files outside of the intended directory, such as ../../etc/passwd, which could expose sensitive system files containing user credentials.
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Information Disclosure: Attackers can access sensitive files containing passwords, configuration files, or other confidential information, leading to data breaches or unauthorized access.
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File Manipulation: Directory Traversal can allow attackers to modify or delete critical files, compromising the integrity of the system or disrupting its functionality.
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Remote Code Execution: In some cases, Directory Traversal vulnerabilities may lead to remote code execution, enabling attackers to execute arbitrary commands on the server or upload malicious scripts for execution.
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Input Validation: Validate and sanitize user input to ensure that file paths or URLs are restricted to the intended directory structure, preventing traversal attacks.
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File System Restrictions: Implement proper file system permissions and access controls to restrict access to sensitive files and directories, preventing unauthorized access.
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Canonicalization: Normalize file paths and perform canonicalization to prevent the interpretation of special characters or sequences that could be used in traversal attacks.
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Security Headers: Use security headers, such as Content Security Policy (CSP), to restrict the sources from which files can be loaded, reducing the risk of Directory Traversal attacks.
Directory Traversal is a security vulnerability that allows attackers to access files or directories outside of the intended directory structure, leading to information disclosure, file manipulation, or remote code execution. By implementing security measures such as input validation, file system restrictions, canonicalization, and security headers, developers can mitigate the risk of exploitation and protect their systems from Directory Traversal attacks. Regular security audits and updates are essential for maintaining a secure file system and web application environment.