Maria works as a professional Ethical Hacker. She is assigned a project to test the security of www.we-are-secure.com. She wants to test a DoS attack on the We-are-secure server. She finds that the firewall of the server is blocking the ICMP messages, but it is not checking the UDP packets. Therefore, she sends a large amount of UDP echo request traffic to the IP broadcast addresses. These UDP requests have a spoofed source address of the We-are-secure server. Which of the following DoS attacks is Maria using to accomplish her task?