Malware types (virus, worm, trojan, ransomware) in Cybersecurity - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a computer virus?

A computer virus is a type of malware that attaches itself to files or programs and spreads when those files are shared or opened. It can damage or delete data and slow down your computer.

beginner

How does a worm differ from a virus?

A worm is malware that can spread by itself over networks without needing to attach to files. It can quickly infect many computers by exploiting network connections.

beginner

What is a Trojan horse in cybersecurity?

A Trojan horse is malware disguised as something harmless or useful. When you open it, it can give attackers access to your computer or steal information.

beginner

What does ransomware do?

Ransomware is malware that locks or encrypts your files and demands money (a ransom) to unlock them. It can stop you from using your own data until you pay.

intermediate

Which malware type spreads without user action?

A worm spreads automatically over networks without needing the user to open files or programs, unlike viruses or Trojans.

Which malware attaches itself to files and spreads when those files are shared?

A Virus

B Worm

C Trojan

D Ransomware

A virus attaches to files and spreads when those files are opened or shared.

Which malware can spread on its own through networks without user help?

A Worm

B Virus

C Trojan

D Ransomware

A worm spreads automatically over networks without needing user action.

What type of malware pretends to be a safe program but actually harms your computer?

A Virus

B Worm

C Trojan

D Ransomware

A Trojan disguises itself as a harmless program to trick users.

Which malware locks your files and demands payment to unlock them?

A Worm

B Ransomware

C Trojan

D Virus

Ransomware encrypts or locks files and asks for money to restore access.

Which malware requires you to open or run a file to infect your computer?

A Worm

B None of the above

C Ransomware

D Virus

A virus needs you to open or run an infected file to spread.

Explain the main differences between a virus, worm, Trojan, and ransomware.

Think about how each malware spreads and what it does to your computer.

Describe a real-life example or situation where ransomware could affect someone.

Imagine losing access to your photos or work documents suddenly.

Practice

1. Which type of malware replicates itself to spread to other computers without needing to attach to a program?

easy

A. Worm

B. Virus

C. Trojan

D. Ransomware

Solution

1. Step 1: Understand malware replication methods

   Viruses need to attach to files, but worms can spread independently over networks.

2. Step 2: Identify malware that self-replicates without a host

   Worms are known for spreading themselves without needing to attach to other programs.

3. Final Answer:

   Worm -> Option A

4. Quick Check:

   Self-replicating malware without host = Worm [OK]

Hint: Worms spread alone, viruses need hosts [OK]

Common Mistakes:

• Confusing virus with worm
• Thinking trojans self-replicate
• Mixing ransomware with spreading behavior

2. Which of the following correctly describes a Trojan horse in malware terms?

easy

A. Malware that replicates itself over networks

B. Malware that encrypts files and demands payment

C. Malware that spreads by attaching to files

D. Malware disguised as legitimate software

Solution

1. Step 1: Define Trojan horse malware

   Trojans appear as normal software but hide harmful actions inside.

2. Step 2: Match description to options

   Malware disguised as legitimate software matches the definition of a Trojan as disguised malware.

3. Final Answer:

   Malware disguised as legitimate software -> Option D

4. Quick Check:

   Trojan = disguised malware [OK]

Hint: Trojans hide inside normal-looking apps [OK]

Common Mistakes:

• Confusing ransomware with Trojan
• Thinking Trojan self-replicates
• Mixing virus and Trojan definitions

3. Consider this scenario: A malware encrypts all files on a computer and demands money to unlock them. What type of malware is this?

medium

A. Ransomware

B. Worm

C. Trojan

D. Virus

Solution

1. Step 1: Identify malware behavior described

   The malware encrypts files and demands payment to restore access.

2. Step 2: Match behavior to malware type

   Ransomware is known for encrypting files and demanding ransom.

3. Final Answer:

   Ransomware -> Option A

4. Quick Check:

   Encrypts files + demands money = Ransomware [OK]

Hint: Ransomware locks files and asks for payment [OK]

Common Mistakes:

• Confusing ransomware with virus
• Thinking Trojan encrypts files
• Mixing worm behavior with ransomware

4. A user reports their computer is slow and programs crash often. They find a malware that attaches itself to files and spreads when files are shared. Which malware type is most likely causing this?

medium

A. Trojan

B. Virus

C. Worm

D. Ransomware

Solution

1. Step 1: Analyze malware behavior

   The malware attaches to files and spreads when files are shared, causing crashes and slowdowns.

2. Step 2: Identify malware type matching this behavior

   Viruses attach to files and spread through sharing, unlike worms which spread independently.

3. Final Answer:

   Virus -> Option B

4. Quick Check:

   Attaches to files + spreads by sharing = Virus [OK]

Hint: Virus attaches to files, spreads via sharing [OK]

Common Mistakes:

• Confusing worm with virus
• Thinking Trojan spreads by itself
• Mixing ransomware symptoms with virus

5. A company wants to protect its network from malware that can spread automatically without user action and also from malware disguised as useful software. Which two malware types should they focus on preventing?

hard

A. Virus and Ransomware

B. Trojan and Virus

C. Worm and Trojan

D. Ransomware and Worm

Solution

1. Step 1: Identify malware that spreads automatically

   Worms spread automatically over networks without user action.

2. Step 2: Identify malware disguised as useful software

   Trojans appear as legitimate software but carry harmful payloads.

3. Final Answer:

   Worm and Trojan -> Option C

4. Quick Check:

   Auto-spread = Worm, disguised = Trojan [OK]

Hint: Worm spreads alone; Trojan hides in apps [OK]

Common Mistakes:

• Choosing ransomware instead of worm
• Mixing virus with Trojan
• Ignoring automatic spread behavior