Attacks — Threats carried out

• Passive — Attempt to learn or make use of information from the system that does not affect system resources.
• Active — Attempt to alter system resources or affect their operation.
• Insider — Initiated by an entity within the security perimeter.
• Outsider — Initiated from outside the perimeter.

Countermeasures are means to deal with attacks, their goal is to prevent, detect, and recover from attacks. They are good at dealing with attacks, but they do not correct or rectify the underlying vulnerability that gave rise to the initial threat. Their intent is to minimize the risk, rather than prevent it entirely.