Malware

Malware is a portmanteau of the words malicious and software. It refers to any software that is deliberately created to cause harm — whether that means damaging hardware, stealing data, or disrupting the user in some other way. The key word is intention: malware is not a bug or an accident, but a program built with a destructive or exploitative purpose.

Over time, many different kinds of malware have been developed, and some have caused damage on a very large scale. Security researchers and organisations have identified many of these programs and built countermeasures against them. Yet new malware continues to appear regularly, and each new variant can compromise the security of computer systems in ways that are hard to quantify. Beyond the technical disruption, malware also causes significant financial losses — worldwide, these damages run into billions of dollars every year.

The main kinds of malware covered here are:

• Viruses — programs that attach themselves to legitimate files or software and spread when those files are executed or shared.
• Worms — standalone programs that replicate themselves and spread across networks without needing a host file.
• Ransomware — malware that locks or encrypts a user's data and demands payment to restore access.
• Trojans — programs that disguise themselves as legitimate or useful software, tricking users into installing them while carrying a hidden malicious payload.
• Spyware — software that secretly monitors user activity and collects information without consent. …