Malicious code / destroyer (malicious codes or abbreviated malcodes) is defined as all kinds of programs, macros or scripts that can be executed and was aimed to damage the computer system. Therefore, a bug that made accidentally by the programmer, not included in this category. But for bugs that really annoying, many people are categorized as malcode.
First used the term “Malware (= Malicious Software)” is intended to malcode. But this term is too weak and narrow, so that bogus e-mail / lie that in fact is not the software cannot be included in this class. Therefore used the term malcode, not malware.
Malicious code can be classified into 3 kinds of groups: viruses, worms and Trojan Horses, and some programs that have bugs.
The virus has a wicked ability to reproduce themselves and consists of a collection of code that can modify the target code is running, or it can also modify the internal structure of the target code, so that the target code before the walk forced to run a virus.
Viruses are often display a message that is not liked, destroy the layout display, delete the C-MOS memory, destroying the information in your hard disk, etc.. Effects of the virus has developed a pretty serious lately.
Examples of viruses: Brain, Ohe half, Die hard, XM / Laroux, Win95/CIH
The virus still can be subdivided into several categories:
Boot Virus: If the computer is turned on, an initial program in the boot sector is executed. Virus in boot sector virus called boot.
File Viruses: File virus is a virus that infects executable program. It is reported that nearly 80% of the virus is a virus file.
Multipartite Virus: A virus that infects both boot sectors and files.
Macro Virus: Recently discovered. The target is not executable programs, but the document files such as Microsoft Excel or Word. He will begin to infect when the application program to read a document that contains macros.
Worm addressed to the program that copies itself to the computer memory ONLY. The fundamental difference from worms and viruses are whether or not to infect the target code. The virus infects the target code, but the worm does not. Worm is staying only in memory.
The worm was initially discovered in large computers (1970s), and only lately found in small computers like PCs. Especially since 1999, which work much e-mail circulated through the media.
Examples of worms: I-Worm/Happy99 (Ska), I-Worm/ExploreZIP, I-Worm/PrettyPark, I-Worm/MyPics
Trojan Horse produced with malicious purpose. Unlike viruses, Trojan horse cannot produce themselves. In general, they were taken by other utility program. Utility programs contain him, or a Trojan Horse itself was “bluff” as a utility program.
Examples of Trojan Horse: Win-Trojan/Back Orifice, Win-Trojan/SubSeven, Win-Trojan/Ecokys (Korean)
Trojan Horse still can be subdivided into:
DOS Trojan Horse: Trojan Horse that runs in DOS. He reduces the speed of your computer or delete files on a particular day or situation.
Windows Trojan Horse: Running on Microsoft Windows systems. Number of Windows Trojan Horse increasing since 1998 and used as a program for hacking with malicious purpose to collect information from the Internet-connected computer.