Question 4 Based on really incident report as given below, answer the following: (b) Why an attack can happen in a network. Provide examples relevant to the case above. [Mark 15]

Reported incidents Denial of Service Attack (February 2000): An attacker just used freely available tools such as TribalFlood Net (TFN) and Trinoo. It has affected popular sites including Yahoo!, Amazon.com, eBay and CNN. The impact: The Yahoo distributed DOS attack which involved 630GB of data. Within a few minutes, the Amazon.com website became 98.5% unavailable to legitimate users. Average performance of the net was "degraded by as much as 26.8%" (Keynote, USA). The consequence: A 17 year-old perpetrator known as MafiaBoy was sentenced to 8 months in youth detention centre. Figure 3.3 The impact of Denial of Service Source: Prof. Steven Furnell, University of Plymouth, UK