1. McLean 20061 HIGHER COMPUTER NETWORKING Lesson 13 Denial of Service Attacks Description of the denial of service attack: effect: disruption or denial of services to legitimate users costs of attack: system downtime, lost revenue and labour involved in identifying and reacting to an attack intent: malicious, personal or political types of attacks: bandwidth consumption, resource starvation, programming flaws and routing and DNS attacks

2. McLean 20062 HIGHER COMPUTER NETWORKING What You Should Know About DOS Attacks Denial of Service (DOS) Attack A DOS attack is an Active attack which disrupts and denies the services provided by a network to legitimate users. Costs Can be vast due to system downtime resulting in lost revenue and the labour required to identify and react to an attack. Motives DOS attacks can be launched for either malicious, personal or political intent.

3. McLean 20063 HIGHER COMPUTER NETWORKING What You Should Know About DOS Attacks Types Of DOS Attacks Attacking routers – corrupted ICMP (Ping) packets divert routers from their normal function and so overloading. Bandwidth Consumption – flooding the network with useless data disabling or crashing a server e.g. e-mail, web. Examples include worms, smurf etc. Resource Starvation – using up a network resource so that legitimate users can’t access it e.g. corrupted packets held in a buffer that can’t be processed Programming Flaws – exploiting bugs in network OS or server software to cause the network servers to crash e.g. PING of Death.

4. McLean 20064 HIGHER COMPUTER NETWORKING What You Should Know About DOS Attacks Types Of DOS Attacks DNS Attacks – a large number of DNS queries sent to a DNS server with ‘spoofed’ IP address. DNS tries to locate fake IP so bandwidth congested and consumed - can even crash DNS server.

5. McLean 20065 HIGHER COMPUTER NETWORKING What You Should Know About DOS Attacks Activity Using the Internet identify a ‘real-life’ example of each of the following: 1.PING of Death 2.Bandwidth consumption 3.DNS attack For each, make a brief note in your jotter. Remember that these could be useful for providing examples in exam questions!