Greg works as a network administrator for a small college. He discovers that several machines on his network are infected with malware. That malware is sending a flood of packets to a target that is external to the network. Which of the following is the BEST description for this attack?

His machines are part of a distributed denial-of-service (DDoS) attack. This scenario describes a generic DDoS, not a specific one like SYN flood, which would involve many SYN packets being sent without a full three-way TCP handshake. These machines could be part of a botnet or they may just have a trigger that causes them to launch the attack at a specific time. The real key in this scenario is the DDoS attack. Finally, a backdoor gives an attacker access to the target system.