Introduction
Malicious software, commonly known as malware, refers to any software designed to harm, exploit, or disrupt computers, networks, or data. It is intentionally created to damage systems, steal information, or spy on users without their consent. Malware can spread through emails, infected websites, USB drives, and software downloads.
What is Malware?
Malware is a broad term that includes various types of harmful programs such as viruses, worms, trojans, ransomware, spyware, adware, and more. These programs can infect a system without the user’s knowledge and perform unauthorized actions.
Categories of Viruses
Computer viruses are a type of malware that attach themselves to legitimate programs or files and replicate when those programs are run. Here are the main categories of viruses:
1. File Infector Virus
This type of virus attaches itself to executable files (.exe or .com). When the file is opened, the virus is activated.
Example: CIH (also known as Chernobyl Virus)
2. Boot Sector Virus
This virus infects the master boot record (MBR) of a hard disk or removable storage. It gets activated when the system starts up.
Example: Michelangelo Virus
3. Macro Virus
These viruses target macro languages in applications like Microsoft Word or Excel. They infect documents and spread when the files are shared.
Example: Melissa Virus
4. Polymorphic Virus
This virus changes its code every time it replicates, making it harder to detect by antivirus software.
Example: Storm Worm
5. Resident Virus
Resident viruses embed themselves into the system memory. They remain active even after the host program is closed.
Example: Randex
6. Multipartite Virus
This type of virus attacks multiple parts of a computer system at once, like files and boot sectors.
Example: Tequila Virus
How Viruses Spread
- Through email attachments
- Infected websites
- Pirated software
- Removable storage devices (USB drives)
- File-sharing networks
Preventive Measures
- Use updated antivirus software
- Regularly update operating system and applications
- Do not click on unknown links or attachments
- Backup important data regularly
Conclusion
Malicious software, especially viruses, pose a serious threat to computer systems and user data. Understanding the different types of viruses helps in identifying, preventing, and removing them effectively. With proper cybersecurity practices, users can protect their systems from virus infections and other types of malware.