virus basics1

8/3/2019 Virus Basics1

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Viruses, Worms, Trojans

andANTI-VIRUSES

Created by:

Arun KumarRoll No. 35

Section-150

www.powerpointpresentationon.blogspot.com


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What is a virus?

A computer virus is a computer programthat can copy itself and infect a computerwithout permission or knowledge of the user.

A virus can only spread from one computer toanother when its host is taken to theuninfected computer, for instance by a user

sending it over a network or the Internet, orby carrying it on a removable medium suchas a floppy disk, CD, or USB drive.


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What is a WORM ?

A computer worm is a self-replicating computerprogram. It uses a network to send copies of itself toother nodes (computer terminals on the network) andit may do so without any user intervention.

Unlike a virus, it does not need to attach itself to anexisting program. Worms almost always cause harmto the network, if only by consuming bandwidth,whereas viruses almost always corrupt or modify fileson a targeted computer.


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What are Trojan Horses ?

A Trojan horse, also known as a trojan, is malwarethat appears to perform a desirable function but infact performs undisclosed malicious functions.Therefore, a computer worm or virus may be a Trojanhorse. The term is derived from the classical story ofthe Trojan Horse.

A program named "waterfalls.scr" serves as a simpleexample of a trojan horse. The author claims it is afree waterfall screen saver. When run, it instead

unloads hidden programs, commands, scripts, or anynumber of commands without the user's knowledgeor consent.


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Types of viruses

Boot viruses Program viruses

Multipartite viruses

Stealth viruses

Polymorphic viruses


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How viruses get intocomputers

The four most common virus infections come from: File A virus type that infects existing files on the computer

(approx. 40% of all viruses)

Macro A virus that runs as a macro in a host application

such as the MS Office applications (approx. 35%)

VBScript A virus that uses Windows VisualBasic Scriptfunctionality (approx. 10%)

Internet Worm A virus that is primarily characterized by

its replication across the Internet (approx. 5%)


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Basic virus defense

Be cautious of files that you are not expecting and fromunknown senders.

Many viruses automatically send files without the email accountowners knowledge. They can piggyback on the email accounts

of senders you know.

Be suspicious of messages that appear more than once in yourInbox

Be aware of sites offering free software downloads


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Basic virus defense (cont.)

Learn file extensions

Your computer will display both an icon and a fileextension for every file.

Open only file extensions you know are safe.


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Examples of risky file types

The following file types should be treated withsuspicion and be confirmed with the sender beforebeing opened:

.exe

.pif .bat

.vbs

.com


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ANTIVIRUS

Antivirus software are computer programs thatattempt to identify, neutralize or eliminate malicioussoftware. The term "antivirus" is used because theearliest examples were designed exclusively tocombat computer viruses; however most modernantivirus software is now designed to combat a widerange of threats, including worms, phishing attacks,Trojans, often described collectively as malware.


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2009 AntiVirus Software ProductComparisons


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Removal Of Some Common Viruses

You can remove some of the commonviruses without help of any antivirusProgram.

Eg : New Folder.exe Autorun.inf ( from PDs etc)


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New Folder.exe

It looks just like an folder but actually it is a exe file.

Step 1: Try deleting the file.

It will delete if you havent executed it, if youre unable to delete it

Go to Task manager ( by pressing ctrl+shift+esc )


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Go to Process Tab andtry finding that the

process for the exe fileand end the process.

Then Go to the same

folder containing theexe file and delete it.

Then Open Search andtry finding the .exe files

of same size and deletethem all.


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Removal of Autorun.inf

Open Run dialog Box. Type in CMDpress ENTER.


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The Command Prompt will Open Now. In Command prompt go to the drivecontaining Autorun.inf

Now Type In attrib hsa and press enter.

This will remove drives attributes for all Hidden, System files.

Now Type Delete autorun.inf and press Enter.

The Virus has been Successfully Removed.


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Any Queries ??


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THANK YOU !!

Reference websites

www.google.com

www.wikipedia.org

Presentation made by:

Lokesh [email protected]

9988105580

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