Ch 3 · 5.3 Cyber Security · O Level Computer Science 2210
Topic 3 of 3 in The Internet and Its Uses — O Level Computer Science 2210 — 29 lessons.
Introduction
Every connected device is a target. Attackers try to steal passwords, money and data, or simply knock websites offline. Knowing how each attack works is the first step to stopping it. (Syllabus section 5.3.)
Key ideas — Threats
🧑🏫 Teacher's explanation
Imagine your computer is a high-security vault. Cyber security threats are the different ways criminals try to crack that vault. Some criminals try every possible combination on the lock one by one (brute-force); others hide inside a delivery truck that you've invited into your garage (Trojan horse); some simply trick you into handing over the keys by pretending to be the bank manager (social engineering).
📖 Definitions
🔍 Worked example — Easy
A user receives an email that looks exactly like it is from their bank. The email claims there is a problem with their account and provides a link to 'verify' their details. Identify the specific cyber security threat and state its primary aim.
🔍 Worked example — Standard
Compare a 'Virus' and a 'Worm' in terms of how they spread.
🔍 Worked example — Exam-style
An attacker uses a script to attempt every possible 4-digit PIN combination (0000 to 9999) on a digital lock. What type of attack is this, and how many attempts are required to guarantee access?
⚠️ Common errors
🧠 Quick check 1
🧠 Quick check 2
🎯 Exam question
(a) Identify one type of malware that can spread across a network without any user intervention. [1] (b) Explain how a 'Phishing' attack differs from a 'Pharming' attack. [2] [3 marks]
Key ideas — Solutions
🧑🏫 Teacher's explanation
Imagine your computer is a high-security building. Cyber security solutions are the layers of protection you put in place to stop intruders. Some solutions are like the physical locks on the doors (authentication), while others are like the security guard at the gate checking IDs (firewalls).
📖 Definitions
🔍 Worked example — Easy
A user receives an email from '[email protected]' asking them to click a link to verify their account immediately. Identify two specific solutions the user could use to prevent a phishing attack.
🔍 Worked example — Standard
Compare the effectiveness of 'Username and Password' versus 'Two-step verification' in the event that a hacker successfully performs a brute-force attack on a password.
🔍 Worked example — Exam-style
A company wants to prevent unauthorized employees from accessing the payroll database while allowing them to access the general company news. Which solution should be implemented?
⚠️ Common errors
🧠 Quick check 1
🧠 Quick check 2
🎯 Exam question
(a) Identify one method of authentication that uses physical characteristics of a person. [1] (b) Explain how 'access levels' would help protect the company's data. [2] [3 marks]
Worked example
A user receives an email that appears to be from her bank, asking her to "verify her account urgently" using a link. Identify the threat and explain two ways she can protect herself.
🔍 Worked example — Easy
A user receives an email from 'Netflix-Support' stating their subscription has expired. The email contains a link: http://netflix-login-secure.net/update. Identify the threat and one specific way to verify if the link is legitimate.
🔍 Worked example — Standard
An employee receives a phone call from someone claiming to be from the IT department. The caller says, 'We are running a security audit and need your password to ensure your account is safe. Please provide it now.' Identify the threat and explain why this is a security risk.
🔍 Worked example — Exam-style
A student is browsing a website and notices the URL starts with https:// and there is a padlock icon in the address bar. Explain what this indicates and identify one way the student could have been targeted by a different threat if they had clicked a link in a suspicious email instead.
⚠️ Common errors
Common mistakes
Practice
Answers: (1) Many computers in a botnet send huge numbers of requests to a server at once, overloading it, so that the service is unavailable to genuine users. (2) Phishing uses fake emails or messages to lure the user to a fake website; pharming redirects the user to a fake website even when they enter the genuine URL. (3) Malware that encrypts the user's files and demands payment for the key. (4) Even if a password is stolen, the attacker also needs the second step (e.g. a code sent to the user's phone). (5) It monitors traffic in and out of the network and blocks traffic that does not meet its rules. (6) Updates fix known security weaknesses quickly, before attackers can exploit them.