1. 1 3 Computing System Fundamentals 3.7 Utility Software

2. 3.7.2 Anti-virus Software

3. 3 Computer viruses Program code (deliberately written). They replicate. They spread. They usually carry a malicious payload.

4. 4 Computer viruses Even a simple virus with no payload uses system resources and will quickly use all available memory and crash the system.

5. 5 Computer viruses Worm - spreads by itself across a network, no need for human interaction. Trojan - virus disguised as a useful application Spyware - sends system information elsewhere without the user’s permission.

6. 6 Anti-virus software Software that scans arriving files and those already present for virus code patterns and either removes the virus from the file or deletes the file. Compares the bit patterns with a library of known malware code.

7. 7 Anti-virus software The library is known as the virus definition file. More recent systems use heuristics - general patterns of system behaviour that suggest the presence of a virus.