Network Threats and Protection
Why network security matters
Networks are constantly under threat from people trying to steal data, damage systems or disrupt services. You need to know the main threats and the methods used to protect against them.
Common network threats
- Malware – malicious software. Types include viruses (attach to files and spread), worms (self-spreading), trojans (disguised as useful software), spyware (secretly records activity) and ransomware (locks files and demands payment).
- Phishing – fake emails/messages pretending to be a trusted organisation to trick people into revealing passwords or bank details.
- Social engineering – manipulating people (not machines) into giving away information or access, e.g. pretending to be IT support.
- Brute-force attack – trying many password combinations until one works.
- Denial of Service (DoS) – flooding a server with so much traffic that it can't respond to genuine users.
- Data interception / eavesdropping – "packet sniffing" data as it travels across a network.
- SQL injection – entering malicious database commands into an input box to access or damage a database.
Human error
Many breaches come from people, not technology: weak passwords, clicking suspicious links, losing devices, or not installing updates. Staff training is a key defence.
Methods of protection
| Method | What it does |
|---|---|
| Firewall | Monitors and blocks unauthorised traffic in/out of a network |
| Anti-malware / antivirus | Detects, quarantines and removes malicious software |
| Encryption | Scrambles data so intercepted data is unreadable without the key |
| Strong passwords + 2FA | Makes accounts far harder to break into |
| User access levels / permissions | Give each user only the access they need |
| Penetration testing | Deliberately testing a system for weaknesses before attackers find them |
| Physical security | Locks, CCTV and keeping servers in secure rooms |
| Backups & updates | Restore after an attack; patches close known vulnerabilities |
Worked example
A company wants to stop staff passwords being cracked by trying millions of combinations. Which two measures help most?
- Strong passwords (long, mixed characters) make brute force far slower, and 2FA / account lockout blocks repeated attempts. ✓
Common mistakes
- Confusing phishing (fake messages) with social engineering in general (phishing is one type).
- Thinking a firewall removes viruses — that's anti-malware's job; a firewall controls traffic.
- Forgetting that human error is a major cause and that training is a valid protection method.
Exam tips
- Be able to match a threat to a suitable defence (e.g. DoS → firewall/traffic filtering; interception → encryption).
- Learn the malware types and one feature of each.
- For "how to keep a network secure", give several layered measures, not just one.
Key facts to remember
- Threats: malware (virus/worm/trojan/spyware/ransomware), phishing, social engineering, brute force, DoS, interception, SQL injection, plus human error.
- Protections: firewall, anti-malware, encryption, strong passwords + 2FA, access levels, penetration testing, physical security, backups/updates.
- Match each defence to the threat it counters.