"The computer virus is a malicious code that replicates by copying itself to another program." It can destroy a single program or the whole software of the computer system. In the 1970s, the first computer virus was generated, known as "Creeper virus." This virus can affect the computers on the ARPANET.
The viruses are unwanted software programs or piece of code which interfere with the functioning of computer software. They are spread via the contaminated files, data, and insecure networks. Once this type of insecure data, files, or network enters into the system then, it produces the duplicate copies of the virus and ruins the whole computer software.
Types of computer virus
There are several types of computer virus which are given below:
1. File Infector
The File Infector computer virus attaches itself with the executable programs such as word processor, spreadsheet applications and computer games. This virus overwrites the code or inserts infected code into the executable file. This virus also infects a number of operating systems such as Macintosh, Windows, and UNIX.
2. Macro Virus
The Macro virus is written in the macro language, which is used for software programs. This virus targets those applications and software which contain macros. The macro virus has carried out a series of operation which affects the performance of program or software.
3. Browser Hijacker
The Browser Hijacker is a malware program. It can modify the web browser settings without the user’s permission and redirect the user to the websites, but the user is not intended to visit.
4. Polymorphic Virus
The polymorphic virus is a harmful, destructive, or intrusive type of malware. It can change or make it difficult to detect with antimalware programs. The development of this malicious code can arise in a variety of ways such as filenames changes, compression, and encryption with variable keys.
5. Direct Action Virus
The Direct-Action Virus can load with the host program from computer memory. It attacks or starts work immediately and ruin the software. This virus is one of the two main types of file infector virus.
6. Boot Sector Virus
The Boot sector is a virus that can infect the boot sector of a floppy disk or the master boot record of the hard disk. It also affects at a BIOS level; they use DOS commands to spread the other floppy disks.
7. Multi Partite Virus
This virus is a fast-moving virus that uses file infectors or boot infectors to attack the boot sector executable files simultaneously. The multipartite virus infects and spreads in multiple ways. This virus has a dual personality,
8. Memory Resident Virus
The resident virus is the kind of computer virus which hides and stores itself within the computer memory. It can infect any file that runs or executed by the computer. The resident virus will load its replication module into memory, so it does not require to be executed to infect other files. This virus is activated whenever the operating system loads or operates a specific function.
9. Web Scripting Virus
The web scripting virus is a kind of computer security vulnerability through websites which breaks our web browser security. This virus allows the attackers to inject client-side scripting into the web page. It can steal our information from the web browser. This type of viruses is usually used to attack the sites with a larger population such as social networking, e-mail, etc.
10. FAT Virus
The FAT stands for File Allocation Table that is a system which is used for maintaining and accessing information of all files. The FAT is an index which can store the address of all records that are stored on the hard drive. This virus pollutes the file allocation table causing widespread damage.
11. Overwrite virus
The Overwrite virus is a malicious program which will effectively destroy the original program code after infection. It can spread itself by overwriting the data in the system’s memory. Several files lose their original content or data when this virus is activated because it can overwrite the content of the file. It infects the file, folders even programs.
12. Directory Virus
The directory virus changes the path that indicates the location of a file. When the user runs the programs and software that are affected by the directory virus. This virus program also runs in the background.