What is Virus?-Types of Viruses

What is computer virus?

A computer virus is a computer program that can replicate itself and spread from one computer to another. The term virus is also commonly, but erroneously, used to refer to other types of malware, including but not limited to adware and spyware programs that do not have a reproductive ability and a computer virus is an executable program. Depend on the nature of a virus, it may cause damage of your hard disk contents or interface normal operation of your computer.

A computer virus is a program or piece of code that is loaded onto your computer without your knowledge and runs against your wished. Viruses can also replicate themselves. All computer viruses are man-made. A simple virus that can make a copy of itself over and over again is relatively easy to produce. Even such a simple virus is dangerous because it will quickly use all available memory and bring the system to a half. An even more dangerous type of virus is one capable of transmitting itself across networks and bypassing security systems.

Symptoms of a computer virus

1. Reduced memory or disk space.

2. Modification of data.

3. An error message appearing on the computer screen.

4. Files overwritten or damaged.

5. Hard drive erased. Etc…

Types of Viruses

1. Trojan Horse :- A Trojan horse is a malicious software program that hides insides other programs. It enters a computer hidden inside a legitimate program, such as a screen saver. Then it puts code into to operating system that enables a hacker to access the infected computer. Trojan horses do not usually spread by themselves. The malicious functionality of a Trojan Horse may be anything undesirable for a computer user, including data destruction or compromising a system by providing a means for another computer to gain access, thus bypassing normal access controls. They are spread by viruses, worms or downloaded software.

2. Worms :- A Worm is a program that makes and facilitates the distribution of copies of itself for example, form one disk drive to another and it spreads without user interaction. Most worms begin as email attachments that infect a computer when they’re opened. The worm scans the infected computer for files, such as address books or temporary webpaged, that contain email addresses. The worm may do damage and compromise the security of the computer. Worms aren’t always destructive to computers, but usually cause computer and network performance and stability problems.

3. Bootsector Virus :- A boot sector virus is a region of a hard disk, floppy disk or other data storage device that contains machine code to be loaded into RAM by a computer system’s built in firmware. The purpose of a boot sector is to allow the boot process of a computer to load a program stored on the same storage device. The location and size of the boot sector is specified by the design of the computing platform.

4. Rootkit Virus : A rootkit virus is an undetectable virus which attempts to allow someone to gain control of a computer system. Rootkits allow viruses and malware to “hide in plain sight” by disguising as necessary files that your antivirus software will overlook. Rootkits themselves are not harmful, they are simply used to hide malware, bots and worms. The term rootkit comes from the linux administrator root user. These viruses are usually installed by torjans and are normally disguised as operating system files.

5. Spyware :- Spyware is a type of malware installed on computers that collects information about users without their knowledge. It capture what you type in your keyboard, including passwords, and send it to the spyware creator. Spyware can track Internet search habits and can also redirect your web browser to a different website than you intend to go to.