AWS WAF

AWS WAF lets you create rules to filter web traffic based on conditions that include IP addresses, HTTP headers and body, or custom URIs. This gives you an additional layer of protection from web attacks that attempt to exploit vulnerabilities in custom or third party web applications. In addition, AWS WAF makes it easy to create rules that block common web exploits like SQL injection and cross site scripting. AWS WAF allows you to create a centralized set of rules that you can deploy across multiple websites.

This means that in an environment with many websites and web applications you can create a single set of rules that you can reuse across applications rather than recreating that rule on every application you want to protect.