The big idea: A vulnerability is a weakness; an attack is someone using it; a threat is the person who might.
Most successful attacks do not break cryptography. They exploit:
- Software that was never updated
- A password that was guessable
- A person who was helpful
| Vulnerability | What it is | How it is exploited |
|---|---|---|
| Unpatched software | A known flaw, left unfixed | Automated scanning finds it within hours |
| Weak credentials | Guessable or reused passwords | Dictionary attack, or credentials leaked elsewhere |
| Unencrypted traffic | Data readable in transit | Packet sniffing on a shared or public network |
| Open ports and services | More running than is needed | Each one is another way in |
| People | Willing to help, and busy | Social engineering and phishing |
Five more on the guide's list
| Vulnerability | What it is | How it is exploited |
|---|---|---|
| Insecure network protocols | Old protocols such as Telnet, FTP and HTTP send data, including passwords, as plain text | Sniffing or man-in-the-middle reads the password |
| SQL injection | A web form passes what a user types straight into a database query | Typing SQL code into the form makes the database reveal or delete data |
| Cross-site scripting (XSS) | A site displays what users submit without cleaning it | An attacker posts a script that then runs in other visitors' browsers, e.g. to steal their session |
| Weak authentication | Only a password, or no limit on login attempts | Guessing or reusing leaked passwords until one works |
| Zero-day exploit | A flaw the software maker does not yet know about, so no patch exists | Attacked before anyone can fix it: patching cannot help on day zero |
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Packet sniffing
Reading traffic that passes the attacker's machine. On an unencrypted connection everything is legible — which is what public Wi-Fi makes easy.
Man-in-the-middle
Sitting between two parties, relaying and possibly altering. Each believes it is talking to the other. A fake Wi-Fi hotspot is the classic route in.
Denial of service
Overwhelming a service so real users cannot reach it. Distributed (DDoS) uses many machines at once, which is why blocking one address does not help.
Malware
Software that arrives and does harm — a virus attaches to a file, a worm spreads by itself across a network, ransomware encrypts and demands payment.
Social engineering
Attacking the person. Phishing emails, a convincing phone call, or someone held the door. No technical control stops a legitimate user being deceived into acting.
A worm needs no one to click: A virus needs a user to run the infected file. A worm spreads by itself, machine to machine, using a network vulnerability.
That difference is why a worm can cross an organisation in minutes, and why the distinction is examined.
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What makes people the reliable route in
- Urgency defeats caution — "your account will be closed today"
- Authority is rarely questioned — an email appearing to come from a manager
- Under pressure, people follow the fastest path, not the safest
- One person in a thousand clicking is enough, and thousands can be emailed for nothing
- And the attacker used a legitimate account, so nothing looks wrong afterwards
Name the vulnerability, then the attack: "Phishing" alone is a half answer. "Staff have no way to verify an email's sender, so a phishing message asking for credentials is likely to succeed" names the weakness and how it is used.
The vulnerability is the weakness; the attack is what someone does with it.
How this is tested — you must identify specific weaknesses in a described setup and say how each would be exploited. It comes up two ways:
Paper 1 Section A
- Describe common network vulnerabilities, 3-4 marks
- Name the attack being described
- Distinguish a virus from a worm
Paper 1 Section B — case study
- Identify weaknesses in a scenario
- Explain why people are targeted
The classic trap: Naming attacks without the weakness each one needs. A DDoS needs finite capacity; sniffing needs unencrypted traffic; phishing needs staff unable to verify a sender.
A small firm has open guest Wi-Fi with no password, computers that are two years behind on updates, one shared admin password, and staff who have had no security training. Identify the vulnerabilities and how each could be exploited.
Model answer plan
See the answer broken into clear points, with guidance on how each point earns marks.