Which AWS service or feature can help automate mitigation against these attacks?

Explanations:

AWS WAF (Web Application Firewall) is specifically designed to help protect web applications from SQL injection attacks and other common threats by allowing users to create rules that block malicious traffic.

Security groups control inbound and outbound traffic to AWS resources but do not specifically target web application layer threats like SQL injection.

An Elastic Load Balancer distributes incoming application traffic but does not provide direct protection against SQL injection attacks.

Network ACLs provide a layer of security at the subnet level in a VPC but are not designed to mitigate application-level threats such as SQL injection.