Virus Type's

What is a Computer Virus ?

A computer virus, much like a "flu virus", is designed to spread from host to host and has the ability to replicate itself. 

A potentially damaging computer programme capable of reproducing itself causing great harm to files or other programs without permission or knowledge of the user.

Similarly, in the same way that viruses cannot reproduce without a host cell, computer viruses cannot reproduce and spread without programming such as a file or document.

A computer virus is a type of malicious software program ("malware") that, when executed, replicates by reproducing itself or infecting other computer programs by modifying them.Infecting computer programs can include as well, data files, or the "boot" sector of the hard drive. When this replication succeeds, the affected areas are then said to be "infected" with a computer virus.The term "virus" is also commonly, but erroneously, used to refer to other types of malware. "Malware" encompasses computer viruses along with many other forms of malicious software, such as computer "worms", ransomware, Trojan horses, key loggers, rootkits, spyware, adware, malicious Browser Helper Object and other malicious software.

Virus – A program that when run, has the ability to self-replicate by infecting other programs and files on your computer. These programs can have many effects ranging from wiping your hard drive, displaying a joke in a small box, or doing nothing at all except to replicate itself. These types of infections tend to be localized to your computer and not have the ability to spread to another computer on their own. The word virus has incorrectly become a general term that encompasses Trojans, worms, and viruses.

Types of viruses :-

1. Boot Sector :-This type of virus affects the boot sector of a floppy or hard disk.this is a crucial part of a disk, in which information on the disk itself is stored together with a program that makes it possible to boot (start) the computer from the disk.boot sector viruses infect either the master boot record of the hard disk or the floppy drive.
2. File or Program :- when executed, load the virus in the memory and perform predefined functions to infect the system. They infect program files with extensions like .exe, .com, .bin, .drv and .sys. and may more program.
3. Stealth Viruses :- They sometimes remove themselves from the memory temporarily to avoid detection by antivirus. They are somewhat difficult to detect. When an antivirus program tries to detect the virus, the stealth virus feeds the antivirus program a clean image of the file or boot sector.
4. Macro Viruses :- A macro virus is a computer virus that “infects” a Microsoft Word or similar application and causes a sequence of actions to be performed automatically when the application is started or something else triggers it. Macro viruses tend to be surprising but relatively harmless.A macro virus is often spread as an e-mail virus. Well-known examples are Concept Virus and Melissa Worm.
5. Malware :- Malware is programming or files that are developed for the purpose of doing harm. Thus, malware includes computer viruses, worms, Trojan horses, spyware, hijackers, and certain type of adware Worm.
6. Adware :– A program that generates popups on your computer or displays advertisements. It is important to note that not all adware programs are necessarily considered malware.
7. Trojan :– A program that has been designed to appear innocent but has been intentionally designed to cause some malicious activity or to provide a backdoor to your system.
8. Worm :– A program that when run, has the ability to spread to other computers on its own using either mass-mailing techniques to email addresses found on your computer or by using the Internet to infect a remote computer using known security holes.