Malware

Malware = malicious software

• Malware is any program written to harm a computer or steal from it.
• The exam expects you to know the main types and how they differ. Here they are.

Spreading types

• Virus — attaches to a file; runs and spreads when you open that file.
• Worm — spreads by itself across a network, with no file to open. The Morris worm was one.
• Trojan horse — pretends to be useful software, but hides something harmful inside.

Stealing and spying types

• Spyware — secretly records what you do, such as the keys you type (your passwords).
• Adware — floods you with adverts; often bundled with free downloads.

Holding data hostage

• Ransomware — encrypts your files and demands payment for the key to unlock them.
• It has shut down hospitals and companies. The best defence is backups you can restore from.

Covers: IGCSE 5.3 (Cyber security threats), A-Level 6.1, AP CSP Big Idea 5.

Now you try

• First, read three behaviours and name the malware type each one describes.
• Then play defender: ransomware has struck, and you must count how many files your backup can restore.

Common mistakes

• A virus needs a host file to spread; a worm spreads by itself across a network.
• A Trojan hides inside useful-looking software.