Computer Security, Ethics and Safe Practice
What to know
Threats include viruses (attach to files), worms (self-spread across networks), trojans (disguised as useful software), ransomware (encrypts files and demands payment), spyware (secretly collects data) and phishing (fraudulent messages that harvest credentials). Defences are layered: strong unique passphrases, multi-factor authentication, prompt updates, antivirus, a firewall that filters network traffic, encryption of sensitive data, and tested backups. The 3-2-1 rule means three copies of data, on two different media, with one stored off-site.
On ethics and law, software is licensed rather than owned. Freeware is free to use, open source publishes its source code, public domain carries no rights reserved, and pirated copies are illegal. Respect copyright and cite sources to avoid plagiarism, follow acceptable-use policies, protect personal data and other people's privacy, and keep a clean digital footprint. Practise good ergonomics and dispose of e-waste responsibly.
Traps
A firewall blocks traffic; antivirus detects malicious files. Encryption is reversible with a key; hashing is one-way. A backup is a restorable copy for recovery, not an archive kept for long-term reference. "Free to download" is not the same as "free to reuse".
Worked example
A staff PC shows a ransom note: disconnect it from the network, do not pay, alert IT, and restore from the most recent offline backup; then patch the entry point that was used.