A security engineer is reviewing the following piece of code for an internally developed web application that allows employees to manipulate documents from a number of internal servers. Users can…

Indexing is a database optimization technique or a search mechanism, which is irrelevant to preventing web application vulnerabilities like SSRF.

Output encoding protects against Cross-Site Scripting (XSS) by ensuring user-supplied data displayed on a web page is rendered as data, not executable code; it does not protect against vulnerabilities arising from processing user input on the server side (like SSRF).

A code scanner (SAST/DAST) helps identify vulnerabilities in code or applications, but it is a detection tool, not a direct implementation to *prevent* the attack in real-time or mitigate the vulnerability at runtime.

A Web Application Firewall (WAF) is designed to protect web applications from various attacks by filtering and monitoring HTTP traffic between a web application and the Internet. A WAF can inspect incoming requests, including URL parameters, and block malicious inputs that could lead to Server-Side Request Forgery (SSRF) or other URL-based vulnerabilities inherent in processing user-supplied URLs.