Which one of the following is not an online attack?

Online attacks require real-time interaction with a target system (e.g., a login interface), whereas offline attacks occur without direct system interaction, typically after obtaining data like password hashes. A rainbow table attack is an offline method that uses precomputed tables of hash values to reverse-engineer passwords from stolen hash databases, distinguishing it from the other options, which are online.

Why B is correct:Rainbow table attacks are performed offline after an attacker has already acquired a hash (e.g., from a compromised database). The attacker matches the hash against precomputed tables to find the plaintext password, requiring no interaction with the target system during the attack. CNSP classifies this as an offline password recovery technique.

Why other options are incorrect:

A:Brute force attacks involve repeatedly submitting password guesses to a live system (e.g., via SSH or a web login), making it an online attack.

C:Password spraying attacks test a few common passwords across many accounts on a live system, also an online attack aimed at avoiding lockouts.

D:Phishing attacks trick users into submitting credentials through fake interfaces (e.g., emails or websites), requiring real-time interaction and thus classified as online.

References:CNSP "Password Attack Methodologies" (Section on Online vs. Offline Attacks) defines rainbow table attacks as offline and contrasts them with online methods like brute force and phishing.