Introduction to Ethical Hacking
Foundations
The objective of security is the CIA triad - confidentiality, integrity, availability - supported by authentication, authorization, accounting, non-repudiation, and defense in depth. Controls split into preventive, detective, corrective, deterrent, and compensating; a question asking what "detects and records" wants a detective control (IDS, audit logs), not a preventive one.
Memorize the phases of the penetration test lifecycle: footprinting/reconnaissance → scanning and enumeration → gaining access (exploitation) → maintaining access (persistence) → covering tracks, followed by reporting. Exam items often name a single tool and ask which phase it belongs to, so attach tools to phases as you study.
Separate assessment types. A vulnerability assessment identifies and ranks weaknesses without exploiting them; a penetration test proves exploitability and business impact. Black box means zero prior knowledge, white box means full knowledge and credentials, and gray box means partial knowledge - a classic trap, since gray box is never "no knowledge." Active testing directly touches the target; passive testing relies on third-party sources and never packets the target.
Know the actors - white hat, gray hat, black hat, script kiddie, hacktivist, state-sponsored, insider - and the legal boundaries: explicit authorization, defined scope, rules of engagement, a signed get-out-of-jail letter, and an NDA. Unauthorized testing is a crime regardless of good intent, and "hacking back" is not a legal defense.
Worked example
A prospect asks you to test "everything the company owns" with no paperwork. Rule of thumb: no written authorization plus no defined scope means do not touch it. Subsidiaries, partner systems, and cloud-hosted assets each need their own written permission, because scope never inherits automatically.