DirectoryTraversalSchwachstelle

DirectoryTraversal, also known as path traversal or dot-dot-slash, is a web security vulnerability that allows an attacker to access files and directories that are outside of the web root directory. This is typically achieved by manipulating input parameters that are used to reference files on the server. For example, if a web application uses user-supplied input to construct a file path, an attacker might use special characters such as "../" to navigate up the directory tree and access sensitive files or execute arbitrary code.

The vulnerability arises when a web application fails to properly sanitize or validate user input before using it in file system operations. Common examples include:

* Accessing files specified in URL parameters, such as `http://example.com/view.php?file=../../../../etc/passwd`.

* Uploading files where the filename can be manipulated to include path traversal sequences.

* Accessing configuration files or other sensitive data that are not intended to be publicly accessible.

The consequences of a successful directory traversal attack can be severe. Attackers can steal sensitive information, including user credentials, financial data, or proprietary code. They may also be able to deface websites, upload malicious files, or even gain full control of the server.

To mitigate directory traversal vulnerabilities, developers should implement strict input validation and sanitization routines. This includes rejecting input containing path traversal sequences like "../" and ensuring that file access is always confined to the intended directory. Canonicalization of file paths and using absolute paths can also help prevent attackers from manipulating the file system. Employing a deny-by-default approach for file access, where only explicitly allowed files are accessible, is another effective security measure.