Ethical Hacking Essentials Practice Test

In a Smurf attack, the attacker typically spoofs the source IP address. This technique involves sending out ICMP Echo Request packets, which are requests for a ping reply, to a broadcast address with the source address set to that of the intended victim. When devices on the network receive this broadcast, they all respond by sending ICMP Echo Reply packets to the victim's IP address. This results in overwhelming the target with traffic, potentially causing a denial of service.

Spoofing the source IP address is crucial in this attack because it disguises the true origin of the packets, making it appear as though the victim's address is the origin of the traffic. This misdirection not only hides the attacker's identity but also makes it difficult for network defenders to trace the attack back to its source.

In the context of the other options, spoofing the destination IP address would have no effect, as the traffic needs to be directed to the intended target for the attack to be effective. Spoofing the MAC address is not relevant in this scenario because MAC addresses operate at the Data Link Layer and are not used in the routing of traffic over the Internet. Lastly, the subnet mask does not play a role in the mechanics of a Smurf attack.