The correct answer is a brute-force attack because the log entries show repeated failed password attempts for the same root account from the same IP address in rapid succession, which is the hallmark of an attacker systematically trying every possible password combination. This differs from a dictionary attack, which relies on a predefined list of common passwords, but the logs here don’t specify the password patterns, making brute-force the more general and accurate classification. On the ISC2 Certified in Cybersecurity CC exam, this scenario tests your ability to distinguish attack types from log evidence, a common task in incident detection. A frequent trap is confusing brute-force with a denial-of-service attack, but remember that while brute-force may degrade performance, its primary goal is unauthorized access, not service disruption. Memory tip: “Same IP, same user, many fails—brute-force never fails to tell the tale.”
ISC2 CC Security Principles Practice Question
This CC practice question tests your understanding of security principles. 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
Refer to the exhibit.
```
Aug 12 14:23:45 server sshd[12345]: Failed password for root from 10.0.0.99 port 54321 ssh2
Aug 12 14:23:46 server sshd[12345]: Failed password for root from 10.0.0.99 port 54321 ssh2
Aug 12 14:23:47 server sshd[12345]: Failed password for root from 10.0.0.99 port 54321 ssh2
Aug 12 14:23:48 server sshd[12345]: Failed password for root from 10.0.0.99 port 54321 ssh2
```
A security analyst observes the log entries on an SSH server as shown. What is the most likely type of attack in progress?
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.
Refer to the exhibit.
```
Aug 12 14:23:45 server sshd[12345]: Failed password for root from 10.0.0.99 port 54321 ssh2
Aug 12 14:23:46 server sshd[12345]: Failed password for root from 10.0.0.99 port 54321 ssh2
Aug 12 14:23:47 server sshd[12345]: Failed password for root from 10.0.0.99 port 54321 ssh2
Aug 12 14:23:48 server sshd[12345]: Failed password for root from 10.0.0.99 port 54321 ssh2
```
A
Dictionary attack
Why wrong: A dictionary attack also uses multiple passwords, but the log does not specify whether passwords are from a dictionary; brute-force is a broader term.
B
Privilege escalation
Why wrong: Privilege escalation would occur after gaining access, not during login attempts.
C
Brute-force attack
Multiple rapid failures from the same IP indicate an automated brute-force attempt to guess the password.
D
Denial-of-service (DoS) attack
Why wrong: A DoS aims to overload the service, not to gain access.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Brute-force attack
Option B is correct because repeated failed password attempts for the same account (root) from the same IP in rapid succession is characteristic of a brute-force attack. Dictionary attack (A) uses a list of common passwords, but the log does not show different passwords; it could be either, but brute-force is more general. (C) is wrong because it's not a DoS (though it might degrade performance). (D) is wrong because there is no indication of privilege escalation beyond root attempts.
Key principle: Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Dictionary attack
Why it's wrong here
A dictionary attack also uses multiple passwords, but the log does not specify whether passwords are from a dictionary; brute-force is a broader term.
✗
Privilege escalation
Why it's wrong here
Privilege escalation would occur after gaining access, not during login attempts.
✓
Brute-force attack
Why this is correct
Multiple rapid failures from the same IP indicate an automated brute-force attempt to guess the password.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Authentication checks who the user is.
✗
Denial-of-service (DoS) attack
Why it's wrong here
A DoS aims to overload the service, not to gain access.
Common exam traps
Common exam trap: authentication is not authorization
Logging in proves the user can authenticate. It does not automatically mean the user is allowed to enter privileged or configuration mode. Watch for AAA authorization, privilege level and command authorization details.
Detailed technical explanation
How to think about this question
This kind of question is testing the difference between identity and permission. A user may successfully log in to a router because authentication is working, but still fail to enter configuration mode because authorization is missing, misconfigured or mapped to a lower privilege level.
KKey Concepts to Remember
Authentication checks who the user is.
Authorization controls what the user is allowed to do after login.
Privilege levels affect access to EXEC and configuration commands.
AAA, TACACS+ and RADIUS can separate login success from command access.
TExam Day Tips
→Do not assume successful login means full administrative access.
→Look for words such as cannot enter configuration mode, privilege level, authorization or command access.
→Separate login problems from permission problems before choosing the answer.
Key takeaway
Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
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. Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access. 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.
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related CC questions on access control and AAA configuration.
Security Principles — This question tests Security Principles — Authentication checks who the user is..
What is the correct answer to this question?
The correct answer is: Brute-force attack — Option B is correct because repeated failed password attempts for the same account (root) from the same IP in rapid succession is characteristic of a brute-force attack. Dictionary attack (A) uses a list of common passwords, but the log does not show different passwords; it could be either, but brute-force is more general. (C) is wrong because it's not a DoS (though it might degrade performance). (D) is wrong because there is no indication of privilege escalation beyond root attempts.
What should I do if I get this CC question wrong?
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related CC questions on access control and AAA configuration.
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?
Authentication checks who the user is.
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