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Presented to Mam Maria Ramzan

COMPUTER VIRUSES

AndAnti Viruses

Overview

What is anti virus? & short history of it.

How an antivirus work? Configuring antivirus software? Some of the symptoms of an

infected computer? Deleting Identified Virus files

manually? Antivirus Effectiveness. Antivirus Damaged files. Online Antivirus scanning. some popular Antivirus.

What is Computer Virus..??Computer viruses are small software programs that are designed to spread from one computer to another and to interfere with computer operation. It is a program or piece of code that is loaded onto your computer without your knowledge and runs against your wishes. A computer virus might corrupt or delete data on your computer, use your email program to spread itself to other computers, or even erase everything on your hard disk.

Viruses – Types and Examples

1. Boot viruses:This virus infects the hard disks or floppy drives boot sector. This would make the computer unable to boot. These viruses can, however, be avoided by ensuring that the floppy disks and hard drive is well protected. Never start the computer using an unknown disk drive or floppy disk.

Examples: the brain virus -it is the very first wild virus to be created.

2.Overwrite Viruses:These types of viruses delete any information in a file they infect, leaving them partially or completely useless once they are infected. Once in the computer, they replace all the file content but the file size doesn’t change. Unfortunately, you would only clean the infected file by deleting it completely, therefore losing original content.

Examples: Trj. Reboot ,Way and Trivial.88.D

3 .Memory Resident Viruses:They usually fix themselves inside the computer memory. They get activated every time the OS runs and end up infecting other opened files. Their effects include corrupting programs and files that are closed, opened, renamed or copied. They hide in RAM.

Example: CMJ, Meve, Randex and Mrklunky

4 .Direct Action VirusesThese viruses mainly replicate or take action once they are executed. When a certain condition is met, the viruses will act by infecting the files in the directory or the folder specified in the AUTOEXEC.BAT. The viruses are generally found in the hard disk’s root directory, but they keep on changing location.

Example: Vienna virus

5 .Program Viruses:These infect executable program files, such as those with extensions like BIN, COM, EXE, OVL, DRV (driver) and .SYS (device driver). These programs are loaded in memory during execution, taking the virus with them. The virus becomes active in memory, making copies of itself and infecting files on disk.

Examples: Sunday and Cascade

6. Macro VirusesThese viruses infect the files created using some applications or programs that contain macros such as doc, pps, xls and mdb. They automatically infect the files with macros and also templates and documents that are contained in the file. They hide in documents shared through e-mail and networks.

Examples: Relax, bablas and 097M/Y2K

Types other than VirusesVirus HoaxesTrojan HorsesWormsSpamAdware Spyware Malware

How Do Computer Viruses Spread?

Computer viruses usually spread in one of three ways:- •From Removable media.

•From Downloads off the Internet.

•From e-mail attachments.

I. When a virus begins to spread, many program files can become unstable and display warnings.

II. The operating system may not launch properly.

III. Critical files may get deleted automatically and the computer may be running slower than usual.

Computer Virus Symptoms:-

Computer is infected with a virus, it may begin to show a series of Computer Virus symptoms that indicate that a virus is present.

Virus can damage your system:-

A computer virus can do a lot of damage to your system before you even realize that it happened.

Computer Viruses: Quickly spreads from one computer to another computer. It starts by attaching and loading itself onto the computer without your knowledge.

A computer virus can be duplicated.

How to remove a computer virus?

Install and Update the antivirus software on the computer. Then, perform a thorough scan of the computer by using the antivirus software.

Install the latest updates from Microsoft Update on the computer.

Download, install, and then run the Malicious Software Removal Tool to remove existing viruses on the computer.

How to protect your computer against viruses:-

On the computer, turn on the firewall.

Keep the computer operating system up-to-date.

Use updated antivirus software on the computer.

Conclusion..!!

TopicTopic

What is anti virus? Antivirus Software is a computer program that identify and

remove computer viruses, and other malicious software like Worms and Trojans from an infected computer. Not only this, an antivirus software also protects the computer from further virus attacks.

The first anti-virus software in 1987. Fix, a German astrophysicist and amateur computer programmer developed software to combat the first computer virus “in the wild," which means that the virus had escaped the confines of the lab or network .

How an Antivirus works ?

An Antivirus works Using dictionary Approach The antivirus software examines each and every file in a computer and examines its content with the virus definitions stored in its virus dictionary. A virus dictionary is an inbuilt file belonging to an antivirus software that contains code identified as a virus by the antivirus authors.

Continue…………….

Anti-virus applications maintain a database of known viruses and compare scanned files that match the characteristics of known viruses. If a scanned files matches those characteristics of known viruses. If a scanned file matches those characteristics, it is quarantined (which means moved to a new, presumably safe location on disk and renamed, so you can find it should you ever need it) so that it cannot affect other files on your system.

Types of Anti viruses1.AVG

AVG is one of the most popular antivirus programs that can be obtained for free and is easy to download directly from the Internet. It can also work with a number of different Windows systems. It has the ability to hold virus files in quarantine so that they cannot do any harm before they can be checked and deleted.

2.McAfee

McAfee Virus Scan has been the second most popular antivirus programs on the market. It provides for spyware and virus protection under one program, rather than separately as many other programs do. It is necessary downloads when they are required.

3.Norton

There are a number of Norton antivirus programs available which are all produced by Symantec. They have quickly proven themselves to be a market leader when it comes to computer system security. Norton Anti-Virus software programs that searches the computer and deletes any viruses that it finds.

4.Kaspersky

Though Kaspersky is not the most popular of all the antivirus protection programs. However, they still provide a very effective product in the protection against viruses, spyware and Trojan horses.

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5.AdAware Ad Aware provides protection against a large number of cyber security threats that arise from using the Internet. In addition to finding and removing viruses and spyware that can detect key strokes and passwords, it will protect against trojan horses.

Some popular Antivirus:

Antivirus Damaged files

Files which have been damaged by computer viruses are normally damaged beyond recovery. Anti-virus software removes the virus code from the file during disinfection, but this does not always restore the file to its undamaged state. In such circumstances, damaged files can only be restored from existing backups; installed software that is damaged requires re-installation.

Antivirus has become an essential part of modern computer use. Antivirus software has become quite sophisticated, often involving signature-based detection methods, heuristic detection methods, rootkit detection, and real-time scanning to prevent computers from being infected with virus. Antispyware software specifically protects the computer from spyware, which can slow down the computer's performance. Many of the big-name antivirus software companies offer combination packages by bundling together antivirus software. To make things easy. Computer users are urged to keep computers clean and safe, and install high quality antivirus.

  

Conclusion

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