The correct answer is a dictionary attack. This is because the log entries show repeated failed login attempts using different usernames and passwords, which aligns with an attacker using a predefined list of common credentials rather than systematically trying every possible combination. In a dictionary attack vs brute force comparison, the key distinction is efficiency: a dictionary attack relies on a curated wordlist of likely passwords, while a brute force attack exhaustively tests all alphanumeric permutations, which would generate far more random-looking attempts. On the ISC2 Certified in Cybersecurity CC exam, this concept tests your ability to recognize attack patterns from logs, and a common trap is confusing the two when you see many login failures—remember that brute force is exhaustive, dictionary is selective. A helpful memory tip: think of a dictionary attack as flipping through a book of common words, while brute force is like trying every key on a giant keyring until one fits.
ISC2 CC Security Operations Practice Question
This CC practice question tests your understanding of security operations. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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.
Exhibit
Feb 12 10:23:45 server1 sshd[1234]: Failed password for root from 192.168.1.100 port 22 ssh2
Feb 12 10:23:47 server1 sshd[1234]: Failed password for admin from 192.168.1.100 port 22 ssh2
Feb 12 10:23:49 server1 sshd[1234]: Failed password for test from 192.168.1.100 port 22 ssh2
Feb 12 10:23:51 server1 sshd[1234]: Failed password for root from 192.168.1.100 port 22 ssh2
Refer to the exhibit. Based on the log entries, what 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.
Feb 12 10:23:45 server1 sshd[1234]: Failed password for root from 192.168.1.100 port 22 ssh2
Feb 12 10:23:47 server1 sshd[1234]: Failed password for admin from 192.168.1.100 port 22 ssh2
Feb 12 10:23:49 server1 sshd[1234]: Failed password for test from 192.168.1.100 port 22 ssh2
Feb 12 10:23:51 server1 sshd[1234]: Failed password for root from 192.168.1.100 port 22 ssh2
A
Brute-force attack.
Why wrong: Brute force usually focuses on many passwords for one username.
B
Dictionary attack.
Multiple usernames tried suggests a dictionary of common names.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Dictionary attack.
The log entries show repeated failed login attempts using different usernames and passwords, which is characteristic of a dictionary attack where an attacker uses a list of common usernames and passwords to gain unauthorized access. Unlike a brute-force attack that tries all possible combinations, a dictionary attack uses a predefined list of likely credentials, making it more efficient and matching the pattern in the logs.
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.
✗
Brute-force attack.
Why it's wrong here
Brute force usually focuses on many passwords for one username.
✓
Dictionary attack.
Why this is correct
Multiple usernames tried suggests a dictionary of common names.
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.
✗
Privilege escalation.
Why it's wrong here
Privilege escalation involves gaining higher access, not login attempts.
✗
Denial of service.
Why it's wrong here
No indication of service disruption.
Common exam traps
Common exam trap: answer the scenario, not the keyword
ISC2 often tests the distinction between a dictionary attack and a brute-force attack, where candidates mistakenly choose 'brute-force' because they see many failed logins, but the key is whether the attempts use a predefined list (dictionary) versus exhaustive character combinations (brute-force).
Detailed technical explanation
How to think about this question
A dictionary attack leverages a precompiled wordlist (e.g., from common passwords or leaked databases) and attempts each entry against a target account, often using tools like Hydra or Medusa. The logs show attempts with usernames like 'admin' and 'root' and passwords like 'password123', which are typical dictionary entries. In contrast, a brute-force attack would iterate through all possible character combinations (e.g., a1b, a1c), which is computationally expensive and would produce a different pattern in logs, such as sequential or incremental changes.
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 security analyst at a medium-sized enterprise encounters this scenario during an investigation or architecture review. The correct answer reflects best practice for the specific threat or control described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Security exam questions test whether you can match controls to threats in context — not just recall definitions.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CC question in full detail.
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: Dictionary attack. — The log entries show repeated failed login attempts using different usernames and passwords, which is characteristic of a dictionary attack where an attacker uses a list of common usernames and passwords to gain unauthorized access. Unlike a brute-force attack that tries all possible combinations, a dictionary attack uses a predefined list of likely credentials, making it more efficient and matching the pattern in the logs.
What should I do if I get this CC 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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