Security · Topic 4 of 5
Threats, Vulnerabilities, Spam, Phishing, Malware and DoS
Learn the difference between a threat and a vulnerability, and recognise spam, phishing, malware and denial of service attacks and the basic defences.
- 4 min
- A threat can cause harm. A vulnerability is the weakness that allows it.
- Spam is unwanted bulk messaging and can carry scams and malicious links.
- Phishing tricks people into giving up private details, and is a kind of social engineering.
What it is
A threat is something that could cause harm, and a vulnerability is a weakness that lets it happen.
Security is about reducing both. You cannot remove every threat, but you can close vulnerabilities and watch for attacks.
This page names the common attacks and shows how a technician helps to stop them.
How it works
Attackers look for a weakness, and defenders find and fix it first.
Threats, vulnerabilities and risk
| Term | Meaning | Example |
|---|---|---|
| Threat | A possible source of harm | A criminal sending phishing emails |
| Vulnerability | A weakness that can be used | Software that is not updated |
| Exploit | A method that uses a vulnerability | A program that attacks the old software |
| Risk | The chance of harm and how bad it would be | A high chance that old software is attacked |
Common vulnerabilities are missing updates, weak or default passwords, open ports that are not needed, and people who can be tricked.
Spam
Spam is unwanted bulk email or messages. It is annoying and can waste time and storage. It is also a common way to deliver scams and malicious links.
Mail filters catch much of it. Users should not reply to spam or click its links.
Phishing
Phishing is a message that pretends to come from a trusted source, such as a bank or a manager, to trick the reader into giving away a password or other private details, or into opening something harmful.
Warning signs are:
- urgent threats or offers that are too good to be true;
- a sender address that is slightly wrong;
- links that go somewhere other than they claim;
- requests for passwords, codes or payments.
Variants include spear phishing, which targets one person or group with a message made for them, smishing, which uses text messages, and vishing, which uses phone calls. All of these are forms of social engineering, which means tricking people instead of attacking machines.
Malware
Malware is software built to cause harm. The main kinds are in the table.
| Type | What it does |
|---|---|
| Virus | Attaches to a file and spreads when the file is run or shared |
| Worm | Spreads across networks by itself, without needing a user to run it |
| Trojan | Pretends to be useful software but hides harmful code |
| Ransomware | Locks files or systems and demands payment to unlock them |
| Spyware | Secretly collects information about the user |
Defences include anti malware software, installing updates quickly, running only trusted software, and careful handling of attachments.
Denial of service
A denial of service attack, or DoS, tries to make a service unavailable. It floods a server or network with so much traffic or so many requests that real users cannot get through.
A distributed denial of service, or DDoS, does the same from many computers at once, often machines that have been taken over with malware. This makes it harder to block, because the traffic comes from many places. A DoS attack is an attack on availability, from the CIA triad.
Basic defences
A few habits cut risk a great deal.
- Keep software and devices up to date.
- Use strong, unique passwords and MFA.
- Use a firewall and anti malware software.
- Take regular backups, kept apart from the main system.
- Train users to spot phishing, and to report anything suspicious.
What to remember for the exam
Seven facts cover most questions on this topic.
- A threat can cause harm. A vulnerability is the weakness that allows it.
- Spam is unwanted bulk messaging and can carry scams and malicious links.
- Phishing tricks people into giving up private details, and is a kind of social engineering.
- Spear phishing targets one person or group. Smishing uses text messages. Vishing uses calls.
- Malware includes viruses, worms, trojans, ransomware and spyware.
- DoS floods a service so it cannot be used. DDoS does it from many computers.
- Updates, strong passwords, MFA, backups and user training reduce risk.
If a message creates urgency and asks for a password or payment, treat it as phishing until you have checked it another way.
Common mistakes
These four errors appear again and again.
Mixing up a threat and a vulnerability. The threat is the danger. The vulnerability is the weakness it uses.
Confusing a virus with a worm. A worm spreads by itself. A virus needs a file to be run or shared.
Clicking to check a suspicious link. Check it another way instead.
Thinking a DoS attack steals data. It attacks availability.
Never give a password or a one time code to someone who contacts you, even if they say they are from IT support.
Check yourself
Work through these three questions.
What is the difference between a threat and a vulnerability?
A threat is something that could cause harm. A vulnerability is the weakness that lets it happen.
How does a worm differ from a virus?
A worm spreads across networks by itself, while a virus attaches to a file and spreads when the file is run or shared.
Which part of the CIA triad does a DoS attack harm?
It harms availability, because the service cannot be used.
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