Final answer:
The security analyst's evidence suggests that the user's account is experiencing a brute-force attack, indicated by the repetitive account lockouts. This type of attack involves systematically guessing the correct password, which contrasts with a password-spraying or dictionary attack, which use fewer password attempts across many accounts or from a list respectively. Implementing strong defensive measures like MFA is recommended.
Step-by-step explanation:
Hackers utilize different strategies to gain unauthorized access to user accounts, and understanding the nature of the attack is crucial for an effective defense. The description provided suggests an attack that repeatedly tries different passwords against one account. This account lockout is indicative of a brute-force attack, option 3, where the attacker systematically checks all possible passwords until the correct one is found.
In contrast, a dictionary attack uses a list of potential passwords, usually derived from words found in a dictionary or commonly used passwords. A password-spraying attack differs by attempting a few commonly used passwords against many different accounts. Finally, a rainbow table attack uses precomputed tables to reverse cryptographic hash functions and reveal passwords, not usually causing account lockouts with multiple login attempts.
Given the evidence of constant lockouts, we can infer that the attacker is not being subtle, leading to the conclusion that a brute-force strategy is at play. Effective countermeasures may include implementing account lockout policies, using complex and unique passwords, and employing multi-factor authentication (MFA).