If you are using a computer, you must hear about computer viruses. This post is also about what are computer viruses and their types.
A computer virus is a special type of program written by a hacker to either harm your computer or gain any type of access to other computers either specific or in bulk as many as he gets.
Type of computer virus
Boot Sector
The boot sector is a reserved part of the storage disk that contains the information that is needed to start the Operating System(OS) of the computer. The boot sector virus infects the boot section and MBR.
This virus attacks the boot section of the system and ensures that the virus is run whenever the system is booting. Boot sector virus code starts running during startup and before security software starts.
And after running it starts infecting other connecting storage disks.
Direct Action
A direct action virus is a virus attached to an executable file that requires action for running. It is designed to target a system, after executing or opening the executable file.
This virus generally comes with attached to popular cracked software. And when you install them, this virus is spread on your system. This virus only spreads when you run the file.
Resident
The resident virus is a virus that is capable of hiding and storing itself in computer memory. From computer memory, it can infect any file that runs on a computer.
This virus loads its replicate module into computer memory. And therefore this virus doesn’t need execution to spread on a computer. This virus is hazardous as it can affect your antivirus software through which it becomes capable of affecting file scans by antivirus programs.
Multipartite
The multipartite virus is a fast-moving virus that infects both the boot sector and the system’s executable file simultaneously. This virus is more dangerous and problematic than other viruses.
Multipartite viruses infect the system multiple times at a regular interval of time. This virus spread itself throughout the entire system. And when this virus is triggered, it automatically launches destructive payloads throughout all computer files.
Polymorphic
A polymorphic virus is a type of computer worm that is not easy to detect in an infected system because it transforms its structure as it propagates.
This virus employs a polymorphic engine to hide its code using cryptography. The polymorphic engine changes the decryption procedure whenever it replicates. It makes it difficult for antivirus programs to find the virus.
Overwrite
An overwrite virus is a malicious program that affects system files. After infection, it destroys the original program code by overwriting data in system memory.
This virus overwrites infected code which can cause irreparable damage to your system. It makes your computer unresponsive and unstable. Data deleted by this virus is irrecoverable as overwriting is done on disk.
Spacefiller Fills
A spacefiller Fills virus attack systems by filling empty spaces in various files. This virus uses the empty space of files to host the virus. It makes it difficult for anti-virus to detect it.
This virus is also known as the cavity virus. Most of the time, the Spacefiller virus affects your system with the CIH files.
File Infector
File Infector virus is a type of malware that attacks mainly executable files with the purpose of permanent damage or making the file unusable. Mostly this virus infects .com and .exe extension files.
This virus is also known as a file injector. When a file is infected, this virus partially or completely overwrites the file.
Macro
A macro virus is a kind of virus that is written in macro. Macro is a programming language rooted inside software applications like Microsoft Office.
This virus injects its code into a macro attached to popular files related to work like Microsoft Office files. This virus needs human action to spread on your computer.
Rootkit
A rootkit is a type of malware that gives unauthorized access to your computer to hackers. A rootkit virus tries to gain admin-level access. This can also hide other types of malware in your device.
Bad guys use rootkit malware to remotely access your computer, manipulate it, and steal data. Through a rootkit virus, a hacker can do anything on your computer as he has access to the admin level.
Creeper
On the infected computer, the Creeper virus prints a file and displays a message on the screen.“I’m the creeper, catch me if you can!”.
A creeper is considered the first computer virus. Creeper virus didn’t harm the system in any manner but it only annoys the user by just displaying the message over and over again.
ELK cloner
Elk Cloner is a boot sector virus. This virus has a feature to replicate itself onto another computer. Elk Cloner works on Apple II systems.
When the system boots, this virus copies itself into a computer. When a new disk is inserted into the computer, the virus automatically copies itself into a new disk.
Code Red
Code red is a computer worm that attacks a computer running a Microsoft IIS web server. This virus spread itself using a common vulnerability known as Buffer overflow.
Code red is one of the few viruses which can run entirely on memory. This virus leaves no file on the hard drive or any other permanent storage.
Slammer
A slammer virus is a computer virus that uses a DOS(Denial OF Service)attack on some internet host to slow down internet traffic. This virus uses a buffer overflow bug in the Microsoft SQL server.
This virus is a small code that generates a random IP address and sends itself to the generated IP address. A slammer virus can block the network and stop email services.
Commwarrior
The com warrior virus is a Bluetooth worm spread through Multimedia Messaging Services(MMS) and Bluetooth. This virus targets the SymbOS operating system.
This virus reads the local address book and looks for phone numbers. And then start sending an infected message to those numbers.