COMPUTER VIRUS1.doc

موضوع: COMPUTER VIRUS1.doc الإثنين 29 ديسمبر 2008, 1:26 pm

1. Computer Virus FAQ for New Users This FAQ

Answers some of the questions that new users ask about computer Viruses and Trojan horse programs. It also tries to clear up some common misconceptions about viruses and E-mail. If you need help with a virus infection or want more advanced information about viruses, please see 'dealing with virus infections:' and 'Sources of additional information: near the end of this FAQ. And if you don't read anything else, at least read the very first topic: Why should I care about computer viruses? Isn't all this just a bunch of

Hype drummed up by marketing departments for anti-virus software companies?

I'm writing this in early May 1999. For the past week, the alt.comp.virus newsgroup has been flooded with pleas for help from people whose computers were clobbered by the CIH virus, which activated on April 26. Many of those people wound up having to put in large amounts of time and effort to get their computers operational; some people have had to buy replacement chips or pay for a repair shop to get their systems back in operation. And some of those people have lost data they will never be able to replace. Yet the CIH virus was well-known almost a year before it activated, and virtually every single current anti-virus program could handle it. But a lot of people didn't have a-v software, and many of those who did have it didn't use it regularly or keep it updated. So a lot of people lost time, money, and irreplaceable data when the CIH virus activated simply because they didn't take basic precautions to protect themselves. The virus threat is not going away: from reading the alt.comp.virus newsgroup, it's obvious that there are lots of people who would just love to create the same kind of havoc with their own virus creations.

2. What is a computer virus?
A computer program loaded to your computer with-out your knowledge or permission and runs against your wishes. It can replicate it self. All computer viruses are manmade. Computer viruses are every where and it is named with lots of different names which scare the computer users.
There are viruses which play music, change or delete files or display messages.
It is called viruses because they got some thing in common with the biological viruses. A computer virus passes from a computer to computer like a biological virus passes from person to person.
A virus should never call harmless and left on the system, a simple virus can make a copy of it self over and over relatively easy to produce. Even such a simple virus is dangerous because it will use all the available memory and bring the system to the holt. Some viruses are doing so little damage that you are unaware that your computer has been infected.
There are different types of viruses such as:
File infectors: A block of code which attaches itself to another program and it can copy itself in to subsequent applications that you run.
Macro viruses: Marco virus spread much more than other type of viruses as people frequently share data files, it spread round the word in two hours effecting tens of millions of computer.
Worms: it has been made to copy it self from one computer to another over a network.
The latest viruses have been emails viruses.
Different way to be infected:
When you open a file or when you open email is infected with a Marco virus.
When downloading files or programs from browsing the internet.
From infected email message

3. How does a computer get a virus?
The computer virus is the same as human virus, human virus passes from person to person and computer virus passes from computer to computer.
There are many ways to get a computer virus but the common way of getting a virus is from an email attachment and that is come from an effected file connected to an email this attachment can be word files, excel files, JPEGs, GIFs or any type of files.
You can not simply get a virus from reading emails. The virus start it is work when you open and run the attachment.
But there are some new viruses are different like (Klez) because you do not have to open an email attachment to release the virus, just opening the email can release the dangerous bug.
The other ways of getting a computer virus are from a file on a floppy or zip disk or when you use an infected file in a clean computer the file infects the clean computer.
Lots of people download infected files from the internet and they start to share them with there friends, in this way the virus spread very fast to all there computers.
If you found that your computer has been infected you, should assume that every disk or computer that you work with or nearby is infected because most of the viruses are spread very fast in the computer and damage your system.
To reduce the chance of getting a virus you should be really careful with the files you take to your computer even if they are from one of your close friend because most of the time people transfer file with out being

4. What kind of files can spread viruses?

Viruses have the potential to infect any type of executable code, not just the files that are commonly called 'program files'. For example, some viruses infect executable code in the boot sector of floppy disks or in system areas of hard drives. Another type of virus, known as a 'macro' virus, can infect word processing and spreadsheet documents that use macros. And it's possible for HTML documents containing JavaScript or other types of executable code to spread viruses or other malicious code. Since virus code must be executed to have any effect, files that the computer treats as pure data are safe. This includes graphics and sound files such as .gif, .jpg, .mp3, .wav, etc., as well as plain text in .txt files. For example, just viewing picture files won't infect your computer with a virus. The virus code has to be in a form, such as an .exe program file or a Word .doc file, that the computer will actually try to execute.

5. How do viruses spread?

When you execute program code that's infected by a virus, the virus code will also run and try to infect other programs, either on the same computer or on other computers connected to it over a network. And the newly infected programs will try to infect yet more programs. When you share a copy of an infected file with other computer users, running the file may also infect their computers; and files from those computers may spread the infection to yet more computers. If your computer is infected with a boot sector virus, the virus tries to write copies of itself to the system areas of floppy disks and hard disks. Then the infected floppy disks may infect other computers that boot from them, and the virus copy on the hard disk will try to infect still more floppies.

Some viruses, known as 'multipartite' viruses, can spread both by infecting files and by infecting the boot areas of floppy disks.

6. What do viruses do to computers?

Viruses are software programs, and they can do the same things as any other programs running on a computer. The actual effect of any particular virus depends on how it was programmed by the person who wrote the virus. Some viruses are deliberately designed to damage files or otherwise interfere with your computer's operation, while others don't do anything but try to spread them selves around. But even the ones that just spread themselves are harmful, since they damage files and may cause other problems in the process of spreading.

Note that viruses can't do any damage to hardware: they won't melt down your CPU, burn out your hard drive, cause your monitor to explode, etc. Warnings about viruses that will physically destroy your computer are usually hoaxes, not legitimate virus warnings.

7. What is a Trojan horse program?

A type of program that is often confused with viruses is a 'Trojan horse' program. This is not a virus, but simply a program (often harmful) that pretends to be something else.

For example, you might download what you think is a new game; but when you run it, it deletes files on your hard drive. Or the third time you start the game, the program E-mails your saved passwords to another person.

Note: simply downloading a file to your computer won't activate a virus or

Trojan horse; you have to execute the code in the file to trigger it. This could mean running a program file, or opening a Word/Excel document in a program (such as Word or Excel) that can execute any macros in the document.
Floppy disks were factors in the spread of computer viruses.The third factor that led to the creation of viruses was the floppy disk. In the 1980s, programs were small, and you could fit the entire operating system, a few programs and some documents onto a floppy disk or two. Many computers did not have hard disks, so when you turned on your machine it would load the operating system and everything else from the floppy disk. Virus authors took advantage of this to create the first self-replicating programs.

موضوع: رد: COMPUTER VIRUS1.doc الخميس 01 يناير 2009, 12:05 am

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موضوع: رد: COMPUTER VIRUS1.doc الإثنين 05 يناير 2009, 6:56 pm

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