Cyber security threats Cambridge IGCSE Computer Science revision
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In plain words
Anything valuable attracts thieves, and data is valuable. The threats fall into three groups: attacks on the system itself, software designed to do harm, and tricks played on people.
8 things to know
- Hacking is gaining unauthorised access to a computer system. A brute-force attack tries every possible combination of characters until it finds the password.
- Data interception is stealing data while it is being transmitted, for example with software that examines packets.
- A distributed denial of service (DDoS) attack floods a web server with a huge number of requests from many computers at once, so that it cannot respond to real users.
- Malware is software designed to do harm. A virus copies itself and attaches to files, and can delete or corrupt data. A worm copies itself and spreads across networks on its own. A Trojan horse is disguised as harmless software.
- More malware: spyware records what the user does, such as key presses, and sends it to someone else. Adware fills the screen with unwanted adverts. Ransomware encrypts the user's files and demands payment to unlock them.
- Phishing is sending an email that pretends to be from a real organisation, with a link to a fake website that asks for personal details.
- Pharming is malicious code that redirects the user to a fake website, even when the correct address is typed.
- Social engineering is manipulating people into giving away confidential information or access.
Worked example
A user receives an email that appears to be from her bank, asking her to click a link and confirm her password. What kind of threat is this, and what is its aim?
- An email pretending to be from a real organisation, with a link, is phishing.
- The link leads to a fake website that looks like the bank's.
- Whatever she types there is collected by the attacker, who can then get into her account.
Tips and tricks
- Phishing needs the user to click a link in a message. Pharming redirects the user without any click, because of malicious code.
- A virus needs a file to attach to and someone to open it. A worm spreads by itself. That is the difference examiners look for.
It lands in your notebook with its questions as flashcards.
Cyber security threats: 7 questions and answers
These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.
What is a brute-force attack?
Longer passwords take far longer to crack this way.
Which malware is disguised as harmless software?
The user installs it willingly, not knowing what it hides.
Which malware records a user's key presses and sends them to someone else?
That is how passwords are stolen.
What is phishing?
It fishes for personal details.
What is the aim of a DDoS attack?
The server is overwhelmed by requests.
What is pharming?
It works even when the correct web address is typed.
Which threat depends on manipulating people more than on technology?Stretch
People are tricked into giving away information or access.
Quiz
7 questions
Tap an answer and you’ll see straight away whether it’s right, and why.
Worksheet
3 questions, 7 marks. Write your answers on paper, then check them.
Cyber security threats
Cambridge IGCSE Computer Science 0478 · 7 marks · papermunch.org
Name ______________________________ Date ______________
Describe the difference between a virus and a worm.[2]
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A virus attaches itself to a file or program and spreads when that file is opened. A worm copies itself and spreads across a network without needing a file or any action by the user.
Describe how a distributed denial of service (DDoS) attack is carried out and what its aim is.[3]
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Many computers are used to send a huge number of requests to a web server at the same time. The server cannot cope with them all. The aim is to stop the server responding to real users, so the website is unavailable.
Describe what is meant by ransomware.[2]
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Malware that encrypts the user's files. A payment is demanded for the key to decrypt them.
Answers: Cyber security threats
- 1. A virus attaches itself to a file or program and spreads when that file is opened. A worm copies itself and spreads across a network without needing a file or any action by the user.
- 2. Many computers are used to send a huge number of requests to a web server at the same time. The server cannot cope with them all. The aim is to stop the server responding to real users, so the website is unavailable.
- 3. Malware that encrypts the user's files. A payment is demanded for the key to decrypt them.