11-08-2012, 11:13 AM
Computer Viruses
Computer Viruses.ppt (Size: 1.76 MB / Downloads: 69)
Introduction
Malicious software is one of the greatest threats to computers and computer networks today
New malicious software is found every day, some of it with the ability to spread globally within hours
The most damaging kinds of malicious software:
Viruses
Programs that can pass on malicious code to other non-malicious programs by modifying them
Viruses attach themselves to just about any type of file
Worms
Primary difference between viruses and worms is that worms operate through networks and viruses spread through any medium
A single virus or worm can cause a billion dollars worth of damage
This presentation will focus on viruses
WHAT IS COMPUTER VIRUS
Virus : -Vital Information Resources Under Seige.
A virus is a program that can pass on malicious code to other non-malicious programs by modifying them.
Virus is a code that attaches itself to a program and propagates copies of itself to other programs.
Classifying Virus -
Polymorphic virus: A polymorphic virus not only
replicates itself by creating multiple files of itself,
but it also changes it's digital signature every time it
replicates.
Boot Sector Virus: A computer virus that infects the
sectors on a disk that contain the data, a computer
uses during the boot process.
Example: Macro Virus
WHAT IS Macro Virus?
A type of computer virus that is encoded as a macro embedded in a document.
According to some estimates, 75% of all viruses today are macro viruses.
Once a macro virus gets onto your machine, it can embed itself in all future documents you create with the application.
In many cases macro viruses cause no damage to data; but in some cases malicious macros have been written that can damage your work.
How Virus Spreads
A virus runs first when a legitimate program is executed.
The virus loads itself into memory and looks to see if it can find any other programs on the disk.
If it can find one, it modifies it to add the virus's code to the new program.
After launching the program the virus now reproduced itself, so two programs are infected.
The next time either of those programs gets executed, they infect other programs, and the cycle continues.
Protection/Prevention
Update your system with Windows Update and Office Update with Proper configurations
Run a secure operating system like Linux
Never double click on an attachment that contain an executable program attachment that comes in as word files (.doc), spreadsheets (.xls), images (.gif or .jpg) etc.
Use original Anti-virus software
How to clean virus?
All activities on infected machine should be stopped and it should be detached from the network.
Recover from backup is the most secure and effective way to recover the system and files.
In some cases, you may recover the boot sector, partition table and even the BIOS data using the emergency recovery disk.
In case you do not have the latest backup of your files, you may try to remove the virus using anti-virus software.
Conclusion
We have to know more about computer virus to know:
How they works on computer
How we can prevent them
What are precautions we can take
So,
Be careful when use new software and files
Be alert for virus activities
Be calm when virus attacks