Malware

Forms of attack: Malware

1.4.1 Threats to computer systems and networks

Threats to computer systems and networks — Note 2 of 7

What you need to know

Malware (malicious software) is an umbrella term for hostile software designed to damage systems, steal data, or gain unauthorised access. Key types include viruses, trojans, and spyware.

What to know

Key terms

Exam tipCommon mistake

Malware: An umbrella term for any software designed to damage, disrupt, or gain unauthorised access to a computer system.
Virus: Malware that attaches to a legitimate program/file and spreads when the infected file is opened. Can corrupt/delete data or slow systems.
Trojan: Malware disguised as legitimate software. Once installed, it creates backdoors for hackers to control the system, steal data, or install more malware.
Spyware: Malware that secretly gathers information (keystrokes, login details, browsing habits) and sends it to the attacker.
Exam tip: 'Keylogger' is a type of spyware — do not list it as a separate threat from spyware.
Worm: Malware that replicates itself across a NETWORK without needing to attach to a file. Uses up bandwidth and can slow or crash networks.
Ransomware: Malware that encrypts/locks access to files and demands payment (ransom) for the decryption key.

Exam technique

Tip:Know the key DIFFERENCE between each type: virus = attaches and spreads; trojan = disguises itself; spyware = secretly monitors; worm = self-replicates across networks; ransomware = locks data for payment.
Mistake:Saying a trojan 'spreads like a virus'. A trojan does NOT spread — it disguises itself and tricks the user into installing it.

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