1) The CIA Triad (the core security goals)

• Confidentiality: Only authorized people can access the data (privacy).
• Integrity: Data is accurate and hasn’t been changed improperly.
• Availability: Systems/data are accessible when needed (uptime).

2) Authentication vs Authorization

• Authentication = proving who you are (login).
• Authorization = what you’re allowed to do (permissions).

3) Common threats

• Phishing: tricking users into revealing credentials or running malware.
• Malware: harmful software (virus, worm, trojan, ransomware, spyware).
• Credential attacks: password spraying, brute force, stolen passwords.
• Unpatched systems: attackers exploit known weaknesses.
• Misconfiguration: overly open permissions, default passwords, exposed services.

4) Controls (how we reduce risk)

Preventive controls

• MFA, strong passwords, least privilege
• Firewalls, secure configuration, patching
• Encryption

Detective controls

• Logging & monitoring
• Antivirus/EDR alerts
• Intrusion detection systems

Recovery controls

• Backups (3-2-1 rule)
• Disaster recovery plan
• Incident response steps

5) Encryption (at rest vs in transit)

• At rest: protects stored data (disk encryption, encrypted database fields).
• In transit: protects data moving across networks (TLS/HTTPS).

6) Patching and updates

Patches fix known vulnerabilities. Attackers often exploit old, unpatched software because it’s the easiest path. A simple update policy prevents a huge percentage of real-world incidents.