# Path Traversal ### Path Traversal Attacks Path traversal attacks, also known as directory traversal attacks, occur when an attacker exploits vulnerabilities in a web application to access files and directories that are stored outside the web root folder. By manipulating variables that reference files with ".." (dot-dot slash sequences), an attacker can read, modify, or delete sensitive files on the server, leading to unauthorized access or system compromise. ### Prevention * **Input Validation:** Validate and sanitize all user inputs, rejecting suspicious patterns. * **Use of Safelists:** Employ safelists for file access and operations, restricting the files that can be accessed. * **Least Privilege:** Ensure the web server process runs with the minimal privileges necessary. * **Updated Libraries:** Keep all server software and libraries updated to mitigate known vulnerabilities. ### **How Path Traversal Attacks Work** At the core of a path traversal attack is the exploitation of the security mechanism that restricts web users to a certain directory—the web root directory. Attackers manipulate variables that reference filesystem paths, using sequences like `../` (dot-dot slash), aiming to break out of this designated directory. For instance, if an application uses unvalidated external inputs to construct file paths, an attacker could craft a request that, instead of accessing intended files (e.g., `webapp/resources/images/logo.png`), accesses sensitive files elsewhere on the server (e.g., `../../etc/passwd`). This kind of attack leverages the fact that `../` is interpreted by the filesystem as a command to move up one directory. Therefore, by repeatedly inserting `../` into file paths, attackers can traverse upward through the directory structure (a technique often called "dot-dot-slash attack") to reach critical system files or other confidential information, far beyond the intended confines of the web application. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://ejpt-certification.certs-study.com/web-attacks/path-traversal.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.