1. DENIAL OF SERVICE ATTACK
YVONNE M. AKUTSA
BEHROKH MOHEB

2. Objectives What is denial of service?
What is distributed denial of service?
Common forms of attack
Modes of attack
Consequences of attack
Real example of attack
Sign of attack
Prevention
Ethic on Denial of Service attack

3. WHAT IS DENIAL OF SERVICE ATTACK?
Denial-of-service attack, is a type of attack on a network that is designed to bring the network to its knees by flooding it with useless traffic. 
DoS attack, denial-of-service attack, is an explicit attempt to make a computer resource unavailable by either injecting a computer virus or flooding the network with useless traffic.

4. WHAT IS DENIAL OF SERVICE ATTACK? cont’
Its aim is to prevent legitimate users by:
Attempting to flood a network
To disrupt connections between computers
Prevent certain individuals from accessing a service
Disrupt service to a specific system or person

5. Common forms of Attack SYN Floods Ping of death Smurf Attack
Teardrop Attack
Mail Bomb
Ping of flood

6. SYN Floods
It takes advantage of the flaw of TCP three-way handshaking behavior.
Sends many requests to the connection.
Do not response to replies.
The SYN flood attack sends TCP connections requests faster than a machine can process them

7. Ping of death
Is a denial of service (DoS) attack caused by an attacker deliberately sending an IP packet larger than the bytes allowed by the IP protocol.  Since the received ICMP(Internet Control Message Protocol) echo request packet is bigger than the normal IP packet size, the victim cannot reassemble the packets. The OS may be crashed or rebooted as a result.

8. Smurf Attack
A smurf attack occurs when an attacker sends a large amount of IP packets to the broadcast address of an intermediate network with spoofed IP addresses as the origin.
 This cause all hosts on the network to reply to the ICMP request, causing significant traffic to the victim's computer.

9. Teardrop Attack Divides large files into fragments.
An attacker sends two fragments that cannot be reassembled properly by manipulating the offset value of packet and cause reboot or halt of victim system.
Teardrop exploits an overlapping IP fragment bug present in Windows 95, Windows NT and Windows 3.1 machines. 

10. Mail Bomb
bombing is characterized by abusers repeatedly sending an message to a particular address at a specific victim site. In many instances, the messages will be large and constructed from meaningless data in an effort to consume additional system and network resources

11. Ping of flood
 Attacker simply sends a huge number of "ICMP Echo Requests(ping)" to the victim.
It sends ICMP packets as fast as possible without waiting for replies.
The continuing combination of requests and replies can slow the network or, in extreme cases, to disconnect.
This is an easy attack because many ping utilities support this operation, and the hacker doesn't need much knowledge.

12. What does the DoS attack?
NETWORK BANDWITH
SERVER MEMORY
CPU USAGE
DATABASE CONNECTION POOL
DATABASE SPACE
HARD DISK SPACE

13. What is Distributed Denial of Service?
DDOS, short for Distributed Denial of Service, is a type of DOS attack where multiple compromised systems , which are usually infected with a Trojan -- are used to target a single system causing a Denial of Service (DoS) attack. 
DDoS = when multiple hosts attack simultaneously
DoS = when a single host attacks.

14. MODES OF ATTACK
Consumption of scarce, limited or non renewable resources
Destruction or alteration of configuration information
Physical destruction or alteration of network components

15. CONSEQUENCES OF ATTACKS
BRAND DAMAGE
FINANCIAL LOSSES
SABORTAGE
EXTORTION
REPEAT ATTACK IF NOT WELL PROTECTED

16. Examples of Attack
Schwab Website Again Hit With Denial of Service Attack ( chwab-website-again-hit-with-denial-of-service- attack/ )
Spamhaus hit by biggest-ever DDoS attacks ( 8/Update_Spamhaus_hit_by_biggest_ever_DDoS _attacks)

17. SIGNS OF AN ATTACK Unusually slow network
Certain websites become slower to open or unavailable.
A high increase in the amount of spam received.
Disconnection of a wireless or wired internet connection

18. PREVENTION OF ATTACK Businesses Firewall and Router configuration
Block unnecessary ports
Filter broadcast messages
Verify source IP address (prevent IP spoofing across subnets)
Install DDoS protection equipment or services
Monitor traffic under normal circumstances and detect anomalies

19. Cont’ Apply latest patches to servers and PCs, Use Antivirus software
Maintain a redundant environment (hot swap server)
End Users
Use a home firewall/router
Apply latest updates for operating system
Use Antivirus software
Use caution when opening attachments or clicking on links

20. ETHICS IN DOS ATTACK
A Denial of Service Attack is unethical. This is because it is an invasion of someone’s space and with others the destruction of property which denies them the right to use what rightfully belongs to them as a legitimate owner.

21. CONCLUSION
Denial of service attacks have now become common forms of protests online for many groups that feel unfairly treated or have prejudices against companies.

22. References http://www.iplocation.net/tools/denial-of-service.php ml
P/SYN_flood/default.htm
death
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