In this following post we will have a little look on what are virus and worm. As told earlier viruses are considered as very first form of computing threats its necessary for a hacker to know what is difference between a virus and worm and what are different types of virus.
What is virus?
A virus is a self replicating program that produces its own code by attaching copies of itself into other executable codes. Like a real virus, a computer virus is contagious and can contaminate other files. Virus can infect outside machines only with assistance of computer users.
Many people think the word virus is derived from real life viruses but this is not true, the word virus is derived from abbreviation of its full form Vital Information Resource Under Seize(VIRUS). Its just coincidence that the abbreviation matches word virus.
Classification Of Virus:
Virus is classified depending on two categories depending on,
What they infect ?
How they infect ?
What they infect?
Boot Viruses: They specially infect boot sector records from hard disk, floppy disk and CD/DVD ROMS.
Program Virus: These virus usually infect executable program files like .exe, .bat, .com, .bin, .ovl, .drv, .sys
Multipartite Virus: These virus infect both boot sector as well as program files.
Network Virus: They spread themselves using emails and flaws in network protocol stack.
Source Code Virus: Source code virus overwrites or appends host code by adding Trojan code in it.
File Virus: File virus generally infects executable files in OS.
Macro Virus: They infect documents, spreadsheets, database, nearly everything that is included as office suite
How they infect ?
Polymorphic Virus: They can change their code with each infection.
Stealth Virus: Can hide from anti-virus programs.
Cavity Virus: Maintains itself with negligible file size and hence after infecting any file the file’s size appears unaltered.
Tunneling Virus: Conceals itself under anti-virus and then infects.
Camouflage Virus: Hides itself in genuine application.
What are worms?
Worms are nothing but subtypes of viruses. Unlike virus a worm doesn’t require a host to replicate. WormsWormsWorm exists in all types of virus since its only modified form of a computer virus. can creep into another computer in network without user’s assistance and hence called as worm. were firstly targeted towards mainframe UNIX systems but today they are very much targeted towards windows OS.