Unit 7 Malicious Logic 1. Define computer virus. What are typical phases of operation of virus? 2. How are Trojan horses differing from viruses? Discuss about possible types of Trojan horses. 3. Define botnet and zombie. 4. What do you mean by DoS and DDoS attack? Describe about Service Overloading and message flooding. 5. Who are intruders? Explain three classes of intruders. 6. Differentiate between HIDS and NIDS. 7. What are approaches to Intrusion Detection? Explain in brief.