Malware is one of the most common and damaging cybersecurity threats. In IB Computer Science, students are expected to understand what malware is, how different types spread, and why they are dangerous. Examiners often test whether students can distinguish clearly between malware types, not just name them.
Three of the most important malware types are viruses, worms, and Trojan horses.
What Is Malware?
Malware is any software designed to:
- Cause harm
- Disrupt systems
- Gain unauthorised access
- Steal data
Malware operates without the user’s informed consent and is a major threat to both individuals and organisations.
In IB terms, malware represents a deliberate security threat.
What Is a Virus?
A virus is a type of malware that:
- Attaches itself to a legitimate file or program
- Requires user action to spread
A virus spreads when:
- An infected file is opened or executed
Key Characteristics of Viruses
- Needs a host file
- Requires user interaction
- Spreads through file sharing, downloads, or removable media
Viruses can:
- Corrupt files
- Slow down systems
- Cause software to behave unpredictably
IB students should emphasise that viruses cannot spread on their own.
What Is a Worm?
A worm is a type of malware that:
- Spreads independently
- Does not need a host file
- Does not require user action
Worms spread by:
- Exploiting network vulnerabilities
- Automatically copying themselves across systems
Key Characteristics of Worms
- Self-replicating
- Spreads rapidly across networks
- Consumes system and network resources
Worms can:
- Overload networks
- Crash systems
- Spread malware payloads
IB examiners often expect students to link worms to network-based attacks.
What Is a Trojan Horse?
A Trojan horse is malware that:
- Disguises itself as legitimate software
- Tricks users into installing it
Unlike viruses and worms:
- Trojans do not self-replicate
Key Characteristics of Trojans
- Relies on deception
- Installed by users unknowingly
- Often opens backdoors or steals data
Trojans are commonly used to:
- Install other malware
- Capture keystrokes
- Grant remote access to attackers
IB students should link Trojans to social engineering.
Comparing Viruses, Worms, and Trojans
A strong IB comparison:
- Virus
- Needs a host file
- Requires user action
- Worm
- Self-spreading
- Exploits network vulnerabilities
- Trojan
- Disguised as legitimate software
- Relies on user deception
Clear distinctions score higher than long descriptions.
Why Understanding Malware Types Matters
Different malware types require:
- Different prevention strategies
- Different detection methods
For example:
- Antivirus software targets viruses
- Firewalls help reduce worm spread
- User education helps prevent Trojans
IB examiners expect students to link malware types to appropriate defences.
Common Student Mistakes
Students often:
- Say all malware self-replicates
- Confuse viruses and worms
- Ignore user involvement
- Give vague definitions
Precision is essential.
How This Appears in IB Exams
IB questions may ask students to:
- Define malware types
- Compare viruses, worms, and Trojans
- Identify malware in a scenario
- Explain how malware spreads
Clear cause-and-effect explanations earn marks.
Final Thoughts
Viruses, worms, and Trojan horses are different types of malware with distinct methods of spread and impact. Viruses rely on infected files, worms spread automatically across networks, and Trojans deceive users into installing malicious software.
Understanding these differences allows IB Computer Science students to analyse malware threats clearly and accurately — exactly what examiners expect.
