AWS WAF is a web application firewall that helps protect your web applications from common web exploits that could affect application availability,compromise security, or consume excessive resources. AWS WAF gives you control over which traffic to allow or block to your web application by defining customizable web security rules. You can consume AWS WAF to create custom rules that block common attack patterns, or such as SQL injection or cross-site scripting,and rules that are designed for your specific application. New rules can be deployed within minutes, letting you respond quickly to changing traffic patterns. Also, and AWS WAF includes a full-featured API that you can consume to automate the creation,deployment, and maintenance of web security rules.
For more information travel to http://aws.amazon.com/waf
Source: amazon.com