What is viruses and worms ?

A Virus is a self replicating program that produces its own copy by attaching itself to another program,computer boot sector or document,Viruses are generally transmitted through file downloads,infected disk/flash drives and as email attachments

Stages Of Virus Life

1).Design - Devolping Virus code using programming languages or construction kits

2).Replication - Virus replicates for a period of time within the target system and then spread itself

3).Launch - It gets Activated with the user performing certains actions such as running an infected program

4). Elimination - Users install antivirus updates and eliminate the virus threats

5). Incorporation - Antivirus Software developers assimilate defenses against the virus

6). Detection - A virus is identified as threat infecting target systems

Working Of Viruses :Infection 

In the infection,the virus replicates itself and attachments to an .exe file in the system

Working Of Viruses : Attack Phases

• Viruses are programmed with trigger events to activate and corrupt systems
• Some viruses infect each time they are run and others infect only when an certain condition is met such as user specific task.

Why Do People Create Computer Viruses

• Inflict damage to competitors
• Financial benefits
• Research projects
• Play Prank
• Vandalism
• Cyber terrorism
• Distribute political messages

Indications of virus attack

Abnormal activities

If the system acts in an unprecedented manner,you can suspect a virus attack

False Positives

However,not all glitches can be attributed to virus attack

How does a Computer Get Infected By Viruses

• Opening infected email attachments
• Installing Pirated software
• Not updating and not installing new versions of plugins
• Not running the latest anti virus application

Virus Hoaxes adn Fake Antiviruses

• Hoaxes are false alarms about non exisiting virus which may contain virus attacks
• Attackers disguises malwares as an antivirus and tricks users to install them in their systems

Macro Viruses

• Macro Viruses infect files created by microsoft word or excel
• Most macro viruses are written using macro language visual basic for application 
• Macro virus infect templates or convert infected documents,templates files,etc,.

Encryption Viruses

• This Type of Virus uses simple encryption to the code
• The Virus is encrypted with a different key for each infected file
• Av scanner cannot directly detect these types of viruses using signature detection methods

Shell Viruses

• Virus code forms a shell around the target host programs code making the original program and host code as its sub routine.
• Almost all boot program viruses are shell viruses