Cyber Security
Internet and Its Uses
(malicious software) is any software written to damage a system, disrupt its operation, or gain unauthorised access to data.
The syllabus names six types of malware.
| Type | What it is and how it works |
|---|---|
| Virus | Malicious code that attaches itself to a file or program and replicates when that file is run, spreading to other files and often corrupting or deleting data. It needs the user to run the infected file (an "active host") to spread |
| Worm | Self-replicating malware that spreads by itself across a network without needing to attach to a file or be run by the user, often consuming bandwidth and slowing systems as it multiplies |
| Trojan horse | Malware disguised as legitimate, harmless software that the user is tricked into installing; once run, it carries out a harmful action such as opening a back door for an attacker. It does not replicate by itself |
| Spyware | Software that secretly monitors and records what the user does, such as logging keystrokes (key-logging) to capture passwords and personal details, and sends the information to the attacker |
| Adware | Software that floods the device with unwanted advertisements; some adware also tracks browsing to target the adverts, and it can slow the system and reduce privacy |
| Ransomware | Malware that encrypts the user's files and then demands a payment (a ransom) in exchange for the key needed to decrypt them, blocking access to the data until the victim pays |
Exam tip
Phishing is a cyber threat but not malware
Malware is software, so when a multiple-choice question asks which threat in a list is not a type of malware, pick the one that is not a program. Phishing is a fake message that tricks the user, so it is the odd one out beside ransomware, a virus and a worm. When you are asked for one more example of malware, choose a type the question has not already named: with those three printed, spyware (a keylogger was accepted too), adware or a Trojan horse each took the mark. The software that finds and removes malware is anti-malware.