Back to: Jss3 Computer Science – ICT (BST)

 Meaning of Computer Viruses

A malware program that can replicate itself by inserting modified copies of itself into other computer programs, data files, or the boot sector of the hard drive is known as a computer virus. Once the replication is successful, the affected areas are then referred to as “infected.” A computer virus can cause serious damage to or even delete data on your computer, use your email program to spread itself to other computers, or even wipe everything on your hard disk. Computer viruses are commonly spread through email messages or instant messaging attachments, infected floppy disks and CD-ROMs, and illegal duplication of software. Repairing the damage caused by a computer virus can be time-consuming and costly. The malfunctioning of some files or the system unit is an indication of a virus in the computer system. For example, when some files on the computer do not respond to commands or cannot be opened, Viruses in the system can also be detected during the scanning of the files in the Central Processing Unit (CPU) with installed anti-virus software.

Some examples of computer viruses include Trojan horse, Sleeper, Logic bomb, Alabama virus, Christmas virus, etc.

Types of computer viruses

There are several types of computer viruses. 

1.   Boot sector virus: a boot sector virus, which infects a storage device’s master boot record (MBR). It is not necessary for a boot sector virus to successfully boot the victim’s PC to infect it. Therefore, even non-bootable media can trigger the spread of boot sector viruses. These viruses copy their infected code to the floppy disk’s boot sector or to the hard disk’s partition table. During start-up, the virus is loaded into the computer’s memory. Once the virus is saved to memory, it infects the non-infected disks used by the computer.

2.  Executable file virus: an executable file virus modifies specific program files, such as. EXE or.COM files. When the program runs, the virus executes by loading itself into memory and later infects and corrupts other files. These viruses are usually spread via infected floppy disks or other removable media, networks, or the Internet. Examples of file or program viruses include Sunday and Cascade, while the sources through which file or program viruses can be infected are the file, the program, the floppy disk, the CD-ROM, and the Internet.

3.  Multipartite Viruses: Multipartite viruses are a type of computer virus that infects multiple target platforms and remains recursively infective in each target. It attempts to attack both the boot sector and the executables, or programs and files, simultaneously. When the virus attaches to the boot sector, it affects the system’s files, and when the virus attaches to the files, it infects the boot sector. This type of virus can reinfect a system repeatedly if all parts of the virus are not eradicated. Examples of multipartite viruses include Ghost ball, Invader, and Flip

Examples of Computer Viruses

1. Trojan: A Trojan virus is a type of malicious software that appears to be harmless but is designed to harm your computer system. It is usually disguised as a legitimate program and once it is downloaded, it can open a backdoor in your system, giving cybercriminals access to your data.
2. Worm: A worm virus is a self-replicating malware that spreads from computer to computer, often through email attachments, instant messaging or social media. Worm viruses can slow down or even crash entire computer networks, causing significant damage.
3. Ransomware: Ransomware is a type of malware that encrypts your files and data, making them inaccessible to you until a ransom is paid to the attacker. Ransomware can be particularly devastating, as it can result in the loss of important data and can also be used to extort money from individuals or organizations.
4. Spyware: Spyware is a type of malware that is designed to collect personal information from your computer system. It can track your online activity, record keystrokes, capture screenshots and steal login credentials. Spyware is often installed without the user’s knowledge, making it difficult to detect and remove.
5. Adware: Adware is a type of malware that displays unwanted and intrusive advertisements on your computer screen. It is often bundled with other free software and can slow down your computer’s performance, cause crashes and consume system resources. Adware can also be used to collect personal information, making it a potential security risk.

It is important to note that these are just a few examples of the many types of computer viruses that exist. Other types include rootkits, boot sector viruses, and file infectors. Regardless of the type of virus, it is important to protect your computer by installing reputable antivirus software, keeping your software up-to-date and being cautious when downloading or installing software from the internet.