Ethical Hacking - Ethical Hacking Phases - Denial of service Attack Tutorial

Denial Of service attack is an attempt  that used to make target resource like websites unavailable for use by huge overloading of traffic ( i.e hitting it with too many request) from single sources at same times.

Effect of Denial Of Service Attack

• Server Failure or Slowdown
• Uncertain increase in spam email received ( this type of DOS attack is considered an e-mail bomb)

Distributed Denial Of Service Attack

Distributed Denial Of service attack is an attempt  that used to make target resource like websites unavailable for use by huge overloading of traffic ( i.e hitting it with too many request) from multiple sources from different location at same times.

These attack are compromised by attacker using a variety of methods.

This attack can also be referred as botnet.

Botnet

 In this attacker use multiple resource as a bot to attack on a target machine. They build bot by spreading malicious code through emails, websites, and social media.

It is also known as zombies.

It spread like worms and viruses.

Once the bot get ready, attacker use multiple bot by sending multiple request to attack target machine.

Types Of DOS Attack

• Ping Of Death Attack
• Smurf Attack
• Buffer Overflow Attack
• Tear Drop Attack
• SYN Attack

• Ping Of Death Attack

In general, ping command is used to check the availability of network resource.

In ping of death , the attacker send  multiple number of packet using a simple ping command.

By the way Internet protocol allow only 65535 bytes data packet to be send.

But the attacker use to send the data packet larger than 65536 bytes.

Since the data packets are larger than what the server can handle, the server can freeze, reboot, or crash.

• Smurf Attack

Smurf Attack is a distributed denial of service attack in which packet flooded on target machine by exploiting ICMP  (Internet Control Message Protocol).

In this large number of packet is created using spoofing. And all this spoofed packet are flooded  to a target machine.

This result in slowing down target machine.

• Buffer Overflow Attack

Buffer are memory storage location that hold data temporarily in RAM. Buffer overflow occur when storage run out of the capacity.

In Buffer overflow attack, attacker tries to overflow data by overwriting the memory with there own executable malicious code. By this way attacker can gain access to target system.

• Tear Drop Attack

A teardrop attack involves sending fragmented packets to a target machine that need to be assembled on the receiving host. Since the machine receiving such packets cannot reassemble them due to a bug in TCP/IP fragmentation reassembly. This bug occur because attacker manipulate the packets. Therefore, packets overlap one another, crashing the target network device. Hence it will slow the system.

• SYN Attack

A SYN Attack is also known as SYN flood attack or half open attack which aims to make a server unavailable to user by consuming all available server resources. By repeatedly sending initial connection request (SYN) packets, the attacker is able to overwhelm all available ports on a target machine, causing the target device in becoming slow or unavailable.