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