Introduction to Computer Viruses PPT Presentation:

The document contains detailed description about computer viruses. Here we will study about the basic definition about virus, its subtypes, how they were recognized and more things about viruses.

                ABOUT VIRUSES

                Basically in bio-logical terms a virus is a non-living thing which cannot produce itself. Similarly computer viruses also cannot produce themselves. Computer viruses is a capable of replicating itself, but the important thing about them is that it can replicate themselves on the same machine without connecting to other machine in the network.

                DISCOVERY OF VIRUS

Virus was first discovered by Farooq Alvi brothers from Pakistan, which was named as dubbed brain. Dubbed brain was called a boot sector virus. Lets us have a look at hoe the virus affect machines. Every virus goes through following phases.

a.)    Dormant Phase:

In this phase virus is activated by when some event is caused on it or caused in machine containing.

b.)    Propagation Phase:

In this phase viruses create an identical copy of themselves and place it in some areas of disk.

c.)     Triggering Phase:

In this phase of virus, viruses actually start working for the purpose yhey are being introduced in the system.

d.)    Execution Phase:

This is the phase where virus damages machine.

Let us have a look at types of viruses.

a.)    Parasitic Virus.

b.)    Memory-Residential Virus.

c.)     Boot-sector Virus.

d.)    Stealth Virus.

e.)    Polymorphic Virus.

Above stated are the types of viruses. Now let us state the classification of viruses.

a.)    Boot Virus.

b.)    DOS Virus.

c.)     Windows Virus.

d.)    Macro Virus.

e.)    Script Virus.

f.)     Java Virus.

g.)    Palm Virus.


Virus starts execution when a program executes. This loads virus in the memory. Virus finds any other program in the memory and alters and changes the virus program. In this way virus launches the real program. In this way virus affect the two files. Some popular viruses are.

a.)    W32 Viruses.

b.)    Melisa.

c.)     Bubble Boy. 

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