Alice works as a Java developer in Fygo software Services Ltd.

The code snippet provided is vulnerable to a Directory Traversal attack. This type of attack occurs when an attacker exploits insufficient security validation/sanitization of user-supplied file names and paths, allowing them to access files or directories that are stored outside the intended folder.

Here’s why the code is vulnerable:

String myfilename = request.getParameter("filename"); This line retrieves the file name from the request’s query string without any validation.

String PathVariable = locationVariable + txtFileNameVariable; This line directly concatenates the user input with the server’s file path, which can be manipulated to traverse directories.

An attacker could manipulate the filename parameter to include sequences like ../ (dot-dot-slash), potentially gaining unauthorized access to files outside the web application’s directory.

To mitigate this vulnerability, Alice should:

Validate the input filename against a whitelist of allowed files.

Use a method to normalize the path, like File.getCanonicalPath(), to resolve any relative path elements and ensure the path is within the intended directory.

Implement proper error handling to avoid revealing sensitive information through error messages.

References:For more detailed information on preventing Directory Traversal vulnerabilities, refer to resources such as the OWASP Foundation1 and other security best practices for Java web applications234.