Firewalk Attack

C.

The Firewalk attack is a technique used to determine what ports on a network are reachable from outside the network, even if the network is protected by a firewall. It is a type of firewall attack and is used to discover hosts behind a firewall device.

The correct answer is C: The Firewalk attack uses traceroute with a predetermined TTL value to discover hosts behind the firewall. The Firewalk attack works by sending packets with incrementing TTL values towards a target host behind the firewall. The firewall will block the packets with a TTL value that is too low, but will allow packets with a TTL value that is just high enough to reach the target host. By carefully selecting the TTL value, the Firewalk attacker can discover the hosts behind the firewall.

Option A is incorrect because while Firewalk attack is a type of firewall attack, it is specifically used to discover hosts behind the firewall and not attack the firewall itself.

Option B is incorrect because Firewalk does not use ICMP sweep. ICMP sweep is used to identify hosts that are alive on a network.

Option D is incorrect because Firewalk is not used to find vulnerabilities in Cisco IOS firewall code. Instead, it is used to determine what ports on a network are reachable from outside the network.

Option E is incorrect because Firewalk does not use an ICMP echo message to discover firewall misconfiguration. ICMP echo is used for ping requests, which are used to determine if a host is alive on the network, and not for discovering firewall misconfigurations.