Security Fundamentals // Lesson 01

Security Concepts.

Define threats, vulnerabilities, exploits and mitigations, then relate risk to likelihood and impact.

ThreatVulnerabilityExploitRiskMitigation
01 // Mental model

Start with the big picture.

A potential cause of harm, such as a malicious actor, malware, accident or environmental event.

CCNA focus: Name each part precisely. A threat is not the same as a vulnerability, and a mitigation reduces risk rather than guaranteeing perfect safety.
02 // Building blocks

Know what each part does.

01

Threat

A potential cause of harm, such as a malicious actor, malware, accident or environmental event.

02

Vulnerability

A weakness in technology, configuration, process or behaviour that could be abused.

03

Exploit

A technique or code that takes advantage of a vulnerability.

04

Mitigation

A safeguard that reduces likelihood, impact or both; residual risk remains after controls.

03 // Compare and recognise

Read the clues.

ItemWhat to remember
ConfidentialityPrevent unauthorised disclosure.
IntegrityPrevent or detect unauthorised modification.
AvailabilityKeep systems and data accessible when needed.
Defence in depthUse multiple complementary controls so one failure is not catastrophic.
04 // Risk scenario

Risk scenario.

Asset: branch router configuration
Threat: credential-stealing attacker
Vulnerability: reused weak administrator password
Exploit: password spraying
Impact: route and ACL changes
Mitigations: MFA, unique secrets, AAA, least privilege, logging

Read the example from top to bottom, then verify the resulting state. Configuration is only complete when the output matches the intended design.

05 // Exam and troubleshooting

Turn facts into a method.

  • Prevent unauthorised disclosure.
  • Prevent or detect unauthorised modification.
  • Keep systems and data accessible when needed.
  • Use multiple complementary controls so one failure is not catastrophic.
Exam checkpoint: Name each part precisely. A threat is not the same as a vulnerability, and a mitigation reduces risk rather than guaranteeing perfect safety.
06 // Check yourself

Security Concepts quiz.

1. What is a vulnerability?

2. What is an exploit?

3. Which CIA property prevents unauthorised modification?

4. What does defence in depth mean?

5. Does mitigation always remove all risk?

Score: 0 / 5