A computer virus is a computer program that can duplicate or copy itself and spread by inserting copies of itself into other programs or documents. Computer viruses can be analogous to biological viruses that spread by inserting itself into living cells. Computer viruses can be destructive (for example by destroying the data on the document), making computer users feel annoyed, or no effect at all.
To further refine our knowledge about the virus, I will try to give an explanation of the types of viruses that often roam in cyberspace.
1. Virus Macro
This type of virus must have been very often we hear. The virus is written in a programming language of an application rather than the programming language of an Operating System. This virus can walk if its constituent applications can run well, that is if the computer can run applications mac word then this virus works on Mac OS bersistem computer.
virus samples:
* W97M variant, for example W97M.Panther
Size: 1234 bytes,
work: It infects the Normal.dot and infected when the document is opened.
* WM.Twno.A; TW
Size: 41,984 bytes,
work: infect documents of Ms. Word's that using macro language, usually DOT and *. DOC *. extension.
2. Virus Boot Sector
Boot sector viruses are spread is very common. The virus is in the doubles he would move or replace the original boot sector virus boot program. So when there is booting the virus will be loaded into memory and then the virus will have the ability to control the standard hardware (ex:: monitor, printer, etc.) and from this memory is also the virus will spread into other existing drives and connected to computer (ex: floppy, drive other than drive c).
virus samples:
*-Variant virus wyx
ex: wyx.C (B) to infect the boot record and floppy;
length: 520 bytes;
characteristics: memory resident and encrypted)
* Variant V-sign:
infect: Master boot record;
520 bytes long;
characteristics: living in the memory (memory resident), encrypted, and polymorphic)
* Stoned.june 4th / bloody!:
infect: Master boot record and floppy;
520 bytes long;
characteristics: living in the memory (memory resident), encrypted and display
message "Bloody! june 4th 1989" after booting the computer as much as 128 times.
3. Stealth Virus
This virus will dominate the table with DOS interrupt table that often we know the "Interrupt interceptor". This virus capable to control the DOS level instruction instructions and they are usually well hidden as a full name or size.
virus samples:
*-Yankee.XPEH.4928,
infect files *. COM and *. EXE;
4298 bytes long;
characteristics: living in memory, the size of the hidden, has a trigger
*-WXYC (which includes any category because the boot record into stealth category also included here)
infect the floppy mother boot record;
520 bytes long;
settled in memory; size and hidden viruses.
*-Vmem (s):
infects files *. EXE, *. SYS and *. COM;
fie 3275 bytes long;
characteristics: living in memory, the size of the hidden, in the encryption.
4.Polymorphic Virus
The virus is designed for misleading anti virus program, meaning the virus is always trying to avoid being recognized by the anti virus with the way the fox is always changing its structure after each infects files / other programs.
virus samples:
* Necropolis A / B,
infect files *. EXE and *. COM;
file 1963 bytes long;
characteristics: settled in memory, the size and viruses hidden, encrypted, and can be changed to change the structure
* Nightfall,
infect files *. EXE;
file 4554 bytes long;
characteristics: settled in memory, the size and hidden viruses, has a trigger, encrypted, and can change the structure.
5. Virus File / Program
This virus infects files that can be executed directly from the operating system, whether application files (*. EXE), as well as *. com are also the result of infection from this virus can be determined by changing the file size is attacked.
6. Multi Partition Virus
This virus is a combination of boot sector viruses and file viruses: it means the work performed resulted in two, that he can infect files *. EXE and also infect the Boot Sector.