Malware
Practise Malware for GCSE Computer Science with this free worksheet and full mark scheme — Foundation and Higher exam-style questions with worked answers. Malware is malicious software; the named forms are computer virus, trojan and spyware.
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These worksheets and mark schemes are original, written for Virtus Academy and checked against the current AQA specification. Every worksheet comes with a full mark scheme.
Topic overview
Malware is malicious software designed to damage or gain unauthorised access to a computer system. Several types must be distinguished.
A virus attaches itself to a file and spreads when that file is opened or shared — it needs a user action to spread. A worm spreads by itself across a network without any user action, which is why worms spread far faster. A trojan disguises itself as legitimate software, so the user installs it willingly.
Spyware secretly monitors activity, often recording keystrokes to capture passwords. Ransomware encrypts the user's files and demands payment for the key. Adware displays unwanted advertisements. The key distinction examiners test is virus against worm: whether a user action is needed to spread.
Revision notes
Viruses and worms
A virus attaches to a file and spreads when that file is opened or shared, so it needs a user action.
A worm spreads by itself across a network with no user action required. This is why worms spread far faster and is the distinction most often examined.
Trojans
A trojan disguises itself as legitimate software.
The user installs it willingly, believing it to be something useful. It does not self-replicate — it relies entirely on deceiving the user into running it.
Spyware, ransomware and adware
Spyware secretly monitors activity, often logging keystrokes to capture passwords.
Ransomware encrypts the user's files and demands payment for the decryption key. Adware displays unwanted advertisements, often bundled with free software.
Key points
- Malware is malicious software.
- A virus attaches to a file.
- A virus needs a user action to spread.
- A worm spreads by itself across a network.
- A trojan disguises itself as legitimate software.
- Ransomware encrypts files and demands payment.
Worked examples
Example 1
State the main difference between a virus and a worm. [2 marks]
Working
Example 2
Explain how ransomware affects a victim. [2 marks]
Working
Example 3
Explain why a trojan is able to get onto a system. [2 marks]
Working
Common mistakes
Confusing viruses and worms.
The distinction is whether a user action is needed to spread.
Saying a trojan self-replicates.
It relies on deceiving the user into installing it.
Naming malware types without describing them.
Say what each one actually does.
Saying ransomware deletes files.
It encrypts them, holding them hostage rather than destroying them.
Exam tips
- Learn the virus-versus-worm distinction precisely.
- Describe what each malware type does.
- Say ransomware encrypts rather than deletes.
- Note that trojans need user installation.
Key terms
- Malware
- Malicious software damaging or accessing a system.
- Virus
- Malware attaching to a file, needing user action to spread.
- Worm
- Malware spreading itself across a network.
- Trojan
- Malware disguised as legitimate software.
Related topics
Written and reviewed against the current AQA specification. Spotted an error? Let us know.