Secure AWS API Gateway with Lambda Integration

Question

I am creating a publicly available API using API Gateway which is backed with lambda functions to do some processing. I have secured it with a custom security header that implements hmac authentication with timestamp to protect against replay attacks. I understand that API Gateway protects against DDOS attacks through its high availability, but any invalid requests will still be passed to the lambda authentication function. So, I guess an attacker can submit invalid unauthenticated requests resulting in high costs. It will take a considerable number of requests to cause damage but it is still very doable. What is the best way to protect against that ? Thank you

Answer 1

To prevent DDoS and higher rate of access, you can setup WAF. Have a look at this link, to get a deeper understanding how to setup WAF with API Gateway.