Network security and threats, use of firewalls, proxies and encryption

1.3.3 Networks

Networks — Note 3 of 5

Candidates need to understand that there are a range of security issues and threats involved with networked computers. Candidates need to be aware of threats such as hackers, viruses, unauthorised access, denial of service, spyware, SQL injection, phishing and pharming. Candidates need to know about ways of minimising, or preventing these threats for example firewalls, secure passwords, anti-virus, anti-spyware etc.

What you need to know

Networked computers face many security threats, from malware to attacks that exploit people or software weaknesses. Firewalls, proxies, encryption and good security practice are used to reduce the risks.

What to know

Threats: hackers gaining unauthorised access; viruses, worms, trojans and spyware; denial of service (DoS) attacks; SQL injection; phishing; pharming.
Other measures: strong passwords, user access levels, anti-malware software, updating software to fix vulnerabilities, input validation to prevent SQL injection, staff training against phishing.

Key terms

Exam tipCommon mistake

Phishing: Fraudulent e-mails or messages that appear to come from a trusted source, designed to trick users into revealing personal details.
Pharming: Redirecting users from a genuine website to a fake one (e.g. by tampering with DNS) to collect their details.
SQL injection: Entering SQL code into an input field so that it is executed by the database, allowing data to be viewed, changed or deleted.
Firewall: Hardware or software that examines incoming and outgoing packets and blocks or allows them according to rules, e.g. by IP address or port number (packet filtering).
Common mistake: Saying a firewall stops all malware. A firewall filters traffic; it does not scan files for viruses.
Proxy server: A server that acts as an intermediary between users and the Internet. It hides users' IP addresses, can filter or block content, and can cache frequently requested pages.
Encryption: Makes intercepted data unreadable without the key, protecting data sent across networks (e.g. HTTPS, Wi-Fi encryption).

Exam technique

Tip:Match each defence to the threat it addresses, and explain HOW it protects the network.

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