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Culture Notes |
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1.Virus
A virus is a self-replicating computer program that interferes with a computer’s hardware or operating system (the basic software that runs the computer). Viruses are designed to replicate and to elude detection. Like any other computer program, a virus must be executed to function — that is, it must be loaded from the computer’s memory, and the virus’s instructions must then be followed by the computer. These instructions are called the payload of the virus. The payload may disrupt or change data files, display a message, or cause the operating system to malfunction.
There are other harmful computer programs that are similar to viruses but do not both replicate and elude detection. These programs fall into three categories: Trojan horses, logic bombs, and worms. A Trojan horse appears to be something interesting and harmless, such as a game, but when it runs it may have harmful effects. A logic bomb delivers its payload when it is triggered by a specific condition, such as when a particular date or time is reached or when a combination of letters is typed. A worm only makes copies of itself, but it can take up computer memory and slow the computer’s processes.
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2. how virus infections occur
Computer viruses spread when the instructions — or executable code — that run programs are exchanged from one computer to another. Once a virus is active, it may replicate by writing itself to flash disks, to the hard drive, into legitimate computer programs, or across computer networks. Such infection is much more frequent in personal computers than in professional mainframe systems because the programs on personal computers are exchanged primarily by means of flash disks or over unregulated computer networks.
Viruses operate, replicate, and deliver their payloads only when they are run. Therefore, if a computer is simply attached to an infected computer network or downloading an infected program, it will not necessarily become infected. Typically a computer user is not likely to knowingly run potentially harmful computer code. However, viruses often trick the computer’s operating system or the computer user into running the viral program.
Some viruses have the ability to attach themselves to otherwise legitimate programs. This attachment may occur when the legitimate program is created, opened, or modified. When that program is run, so is the virus. Viruses can also reside on portions of the hard disk or flash disk that load and run the operating system when the computer is started, and such viruses thereby are run automatically. In computer networks, some viruses hide in the software that allows the user to log on (gain access to) the system.
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hacker
A hacker is somebody illegitimately accessing another’s computer; somebody who uses computer expertise to gain unauthorized access to a computer system belonging to another, either to learn about the system or to examine its data. |
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