John, a malicious hacker, forces a router to stop forwarding packets by flooding it with many open connections simultaneously so that all hosts behind it are effectively disabled. Which of the following attacks is John performing?

A.
Rainbow attack

B.
DoS attack

C.
Replay attack

D.
ARP spoofing

Explanation:
A Denial-of-Service (DoS) attack is mounted with the objective of causing a negative impact on the performance of a computer or network. It is also known as a network saturation attack or bandwidth consumption attack. Attackers perform DoS attacks by sending a large number of protocol packets to the network. The effects of a DoS attack are as follows: Saturates network resources Disrupts connections between two computers, thereby preventing communications between services Disrupts services to a specific computer Causes failure to access a Web site Results in an increase in the amount of spam A Denial-of-Service attack is very common on the Internet because it is much easier to accomplish. Most of the DoS attacks rely on the weaknesses in the TCP/IP protocol. Answer option C is incorrect. A replay attack is a type of attack in which attackers capture packets containing passwords or digital signatures whenever packets pass between two hosts on a network. In an attempt to obtain an authenticated connection, the attackers then resend the captured packet to the system. In this
type of attack, the attacker does not know the actual password, but can simply replay the captured packet. Answer option D is incorrect. Address Resolution Protocol (ARP) spoofing, also known as ARP poisoning or ARP Poison Routing (APR), is a technique used to attack an Ethernet wired or wireless network. ARP spoofing may allow an attacker to sniff data frames on a local area network (LAN), modify the traffic, or stop the traffic altogether. The attack can only be used on networks that actually make use of ARP and not another method of address resolution. The principle of ARP spoofing is to send fake ARP messages to an Ethernet LAN. Generally, the aim is to associate the attacker’s MAC address with the IP address of another node (such as the default gateway). Any traffic meant for that IP address would be mistakenly sent to the attacker instead. The attacker could then choose to forward the traffic to the actual default gateway (passive sniffing) or modify the data before forwarding it. ARP spoofing attacks can be run from a compromised host, or from an attacker’s machine that is connected directly to the target Ethernet segment. Answer option A is incorrect. The rainbow attack is the fastest method of password cracking. This method of password cracking is implemented by calculating all the possible hashes for a set of characters and then storing them in a table known as the Rainbow table. These password hashes are then employed to the tool that uses the Rainbow algorithm and searches the Rainbow table until the password is not fetched.