Computer viruses

Computer viruses

• Created by:-• Jagath• Pankaj• Pratish• Rasika• Niraj

What is a computer virus?• A computer virus is a computer program

that can copy itself and infect a computer without permission or knowledge of the user.

• A computer virus can only spread from one computer to another when its host is taken to the uninfected computer, for instance by a user sending it over a network or the Internet, or by carrying it on a removable medium such as a floppy disk, CD, or USB drive.

History of computer viruses• 1981 Apple Viruses 1, 2, & 3

• 1980’s Fred Cohen

• 1987 Lehigh Virus

• 1988 The first anti virus software

• 1990 The first polymorphic viruses

• 1991 Symantec releases Norton Anti Virus

• 1992 The Michelangelo Virus

• 1994 Kaos4 virus spreads via adult websites.

Virus through the internet

• Today almost 87% of all viruses are spread through the internet.

• Transmission time to a new host is relatively low, on the order of hours to days

• “Latent virus”

Symptoms of virus Attack• Computer no longer boots up.• Screen sometimes flicker.• Computer runs slower then usual.• PC speaker beeps periodically.• System crashes for no reason.• Files/directories sometimes

disappear.• Denial of service (dos)….. & Many

More.

Examples of risky file types

• The following file types should be treated with suspicion and be confirmed with the sender before being opened:– .exe– .pif– .bat– .vbs– .com

What to do when you find viruses

Firstly, you should call the administrator for future action. In some cases it is not good to start you computer from hard disk, because the virus may active and then do some harm.

Make sure that you should get sure that it is virus and what virus it is. It is important to know what kind of virus we are dealing with. Companies that make anti-virus programs know what different viruses do and you can go to their web pages and read about the virus you have.

Cont……

When you start you computer you should do it from a clean (non-infected) floppy diskette and after that run the virus program. The boot diskette should be write protected so that virus can not infect the boot diskette too.

It is good to take a backup of the file that was infected. Virus program could do some damage to the file and that is why it is good to have a backup.

It is good to let you, to know about the virus, so viruses would not spread around so much.

How to protect from viruses Best way to protect yourself is to prepare your computer against viruses in advance. One way to protect you computer is to use updated anti-virus program. When you get an email attachment, you should first check the attachment by checking the file with an anti-virus program. One can protect the computer against boot sector viruses by setting the BIOS to start from a hard disk rather than from a floppy disk. Write protection is a good way to prohibit against viruses. Write protection works well in floppy disks, Windows NT and UNIX, but not that well in Windows and Windows95.

What is a computer WORM ?• A computer worm is a self-replicating

computer program. It uses a network to send copies of itself to other nodes (computer terminals on the network) and it may do so without any user intervention.

• Unlike a virus, it does not need to attach itself to an existing program. Worms almost always cause harm to the network, if only by consuming bandwidth, whereas viruses almost always corrupt or modify files on a targeted computer.

What are Trojan Horses ?

• A Trojan horse, also known as a trojan, is malware that appears to perform a desirable function but in fact performs undisclosed malicious functions. Therefore, a computer worm or virus may be a Trojan horse. The term is derived from the classical story of the Trojan Horse.

• A program named "waterfalls.scr" serves as a simple example of a trojan horse. The author claims it is a free waterfall screen saver. When run, it instead unloads hidden programs, commands, scripts, or any number of commands without the user's knowledge or consent.

Types of viruses

• Boot viruses

• Program viruses

• Multipartite viruses

• Stealth viruses

• Polymorphic viruses

How viruses get into computers

• 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 Script functionality (approx. 10%)

– Internet Worm – A virus that is primarily characterized by it’s replication across the Internet (approx. 5%)

Basic virus defense• Be cautious of files that you are not expecting and from

unknown senders.

• Many viruses automatically send files without the email account owner’s knowledge. They can ‘piggyback’ on the email accounts of senders you know.

• Be suspicious of messages that appear more than once in your Inbox

• Be aware of sites offering free software downloads

Basic virus defense (cont.)

• Learn file extensions– Your computer will display both an icon and a file

extension for every file.

– Open only file extensions you know are safe.

ANTIVIRUS• Antivirus software are computer programs that

attempt to identify, neutralize or eliminate malicious software. The term "antivirus" is used because the earliest examples were designed exclusively to combat computer viruses; however most modern antivirus software is now designed to combat a wide range of threats, including worms, phishing attacks, Trojans, often described collectively as malware.

2009 AntiVirus Software Product Comparisons

Removal Of Some Common Viruses

• You can remove some of the common viruses without help of any antivirus Program.

• Eg : New Folder.exe

• Autorun.inf ( from PDs etc)

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 haven’t executed it, if you’re unable to delete it

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

Go to Process Tab and try finding that the process for the exe file and end the process.

Then Go to the same folder containing the exe file and delete it.

Then Open Search and try finding the .exe files of same size and delete them all.

Removal of Autorun.inf

• Open Run dialog Box. Type in “CMD” press ENTER.

Cont…….• The Command Prompt will Open Now. In Command prompt go to the drive

containing Autorun.inf• Now Type In “ attrib –h –s –a” 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.

Data Fellows F-Prot EliaShim ViruSafe ESaSS ThunderBYTE IBM Antivirus McAfee Scan Microsoft Anti-Virus Symantec Norton Antivirus S&S Dr S&S Dr Solomon's AVTK. Bit Defender 2008

* How computer viruses have spread out around the world *

Computer viruses are a problem all over the world. The following picture tells us how many times people have accessed Data Fellows, a company that makes anti-virus program F-Prot, more than 1,672,846 per month. It means that people are interesting in virus information. One reason is that people have to deal with viruses. Viruses in not only a problem in Finland and USA, it is a problem around the world.

Today's most common virus is the macro virus. Cap virus is one of the macro viruses. Last month there were 3100 Cap macro virus accesses during the last 30 days in Data Fellows. Next common virus was “Join” with 1171 accesses and third common was Pen pal Greetings with 895 accesses.

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conclusion There are lots of viruses in the world and new viruses

are coming up every day. There are new anti-virus programs and techniques developed too. It is good to be aware of viruses and other malware and it is cheaper to protect you environment from them rather then being sorry. There might be a virus in your computer if it starts acting differently. There is no reason to panic if the computer virus is found.

It is good to be a little suspicious of malware when you surf in the Internet and download files. Some files that look interesting might hide a malware.

THE LAST WORD “THE ONLY TRULY SECURE SYSTEM

IS ONE THAT IS POWERED OFF, CAST IN A BLOCK OF CONCRETE, AND SEALED IN A LEAD-LINED ROOM WITH ARMED GUARDS AND EVEN THEN I HAVE MY DOUBTS.”

Keep your pc

safe......./

THANK YOU