This CAS-004 practice question tests your understanding of security operations. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Based on the exhibit, which type of attack is most likely occurring?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Brute force password guessing
The exhibit shows a high number of failed authentication attempts (e.g., Event ID 4625) from a single source IP against multiple user accounts over a short period. This pattern is characteristic of a brute force password guessing attack, where an attacker systematically tries common passwords against many accounts to gain unauthorized access. The absence of successful logins or account lockouts further supports this conclusion.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Pass-the-hash attack
Why it's wrong here
Pass-the-hash uses NTLM hashes, not sudo authentication failures.
✗
Account lockout attack
Why it's wrong here
Account lockout would show lockout messages, not repeated authentication failures.
✗
Replay attack
Why it's wrong here
Replay attacks involve capturing and retransmitting valid credentials, not repeated authentication failures.
✓
Brute force password guessing
Why this is correct
The rapid succession of authentication failures for the root user indicates an attempt to guess the password.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between a brute force attack (many passwords, one account) and a password spraying attack (one password, many accounts), and the trap here is confusing the high volume of failed logins with a replay or pass-the-hash attack, which would show successful authentication or token reuse instead of repeated failures.
Trap categories for this question
Command / output trap
Account lockout would show lockout messages, not repeated authentication failures.
Detailed technical explanation
How to think about this question
In a brute force password guessing attack, the attacker typically uses tools like Hydra or Medusa to iterate through a password list against a target service (e.g., RDP, SMB, or SSH). Windows Security Log Event ID 4625 logs each failed logon attempt with details such as the source IP, target account, and logon type (e.g., 3 for network logon). The attack can be mitigated by account lockout policies (e.g., 5 failed attempts within 15 minutes) or by enabling Windows Defender Firewall with IP allow lists to restrict access.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Security Operations — This question tests Security Operations — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Brute force password guessing — The exhibit shows a high number of failed authentication attempts (e.g., Event ID 4625) from a single source IP against multiple user accounts over a short period. This pattern is characteristic of a brute force password guessing attack, where an attacker systematically tries common passwords against many accounts to gain unauthorized access. The absence of successful logins or account lockouts further supports this conclusion.
What should I do if I get this CAS-004 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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