What is a computer virus and how to protect yourself

A computer virus is a malicious program that infects your computer to steal data, damage the system or spread to other devices. These threats still pose a major risk to individuals and businesses alike.

Definition and how a computer virus works

A computer virus is malicious code designed to attach itself to legitimate files and replicate automatically. Contrary to popular belief, a virus needs a host file to work and cannot run on its own.

The infection process usually follows these steps:

1. the virus enters the system through an infected file,
2. copies itself into other programs,
3. then activates its malicious payload.
   • The payload can range from displaying harmless messages to destroying data.

Viruses differ from other malware in their ability to replicate. They can infect thousands of files in a few minutes and spread through networks, email or removable media.

The most common types of virus

File viruses infect executable programs (.exe, .com) and activate when you launch the infected application. They account for the majority of traditional infections.

Boot sector viruses install themselves in the boot area of the hard drive. Particularly dangerous, they load before the operating system and are hard to detect.

Macro viruses exploit the macros in Office documents. Although less common today, they can still infect via malicious Word or Excel files.

Computer worms spread automatically through networks without a host file. The famous WannaCry worm of 2017 paralysed thousands of computers by exploiting a Windows flaw.

How to protect yourself effectively from viruses

Install a reputable antivirus and keep it constantly up to date. Windows Defender, built into Windows, provides basic protection that is enough for most users.

Avoid suspicious downloads from unreliable sites. Always use official sources for your software and be wary of emails with unexpected attachments.

Keep your system up to date with the latest security patches. Automatic Windows updates regularly close the security holes exploited by viruses.

Make regular backups of your important data to disconnected external media. It is your best insurance against ransomware and destructive viruses.

Use a password manager to have unique, randomly generated and encrypted passwords.

Computer viruses: key takeaways

Computer viruses remain a real threat but are largely avoidable with rigorous security practices. Vigilance and the right tools are your first line of defence against these malicious programs.