CISSP Security Assessment and Testing Practice Question
This CISSP practice question tests your understanding of security assessment and testing. 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.
A security analyst is reviewing logs and notices multiple failed login attempts from a single IP address followed by a successful login. What should the analyst do next?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Investigate the successful login
The correct answer is C because a successful login immediately following multiple failed attempts from the same IP address is a classic indicator of a brute-force or password-spraying attack that succeeded. The analyst must investigate the successful login to determine if it was legitimate or an account compromise, checking for anomalous behavior, time of access, and any subsequent actions. Ignoring or prematurely blocking the IP could destroy forensic evidence or lock out a legitimate user, while disabling the account without investigation may be premature if the login was authorized.
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.
✗
Disable the account immediately
Why it's wrong here
Disabling without investigation may disrupt legitimate use and does not address the root cause.
✗
Ignore, as failed logins are normal
Why it's wrong here
Multiple failures followed by success is not normal and indicates a potential attack.
✓
Investigate the successful login
Why this is correct
The successful login after failures is suspicious and requires investigation to confirm if it was authorized.
Related concept
Read the scenario before looking for a memorised answer.
✗
Block the IP address
Why it's wrong here
Blocking the IP might stop further attempts but does not investigate the successful login.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often jump to a reactive action like blocking the IP or disabling the account, failing to recognize that the immediate priority is to investigate the successful login to confirm compromise and preserve forensic evidence.
Detailed technical explanation
How to think about this question
Under the hood, authentication logs typically record event IDs such as 4625 (failed logon) and 4624 (successful logon) in Windows Security Logs, or syslog entries in Linux/Unix. The analyst should correlate the source IP, timestamp, and target account, then check for post-authentication activity like privilege escalation or data exfiltration. In a real-world scenario, the attacker might have used a password spray tool like Hydra or a dictionary attack, and the successful login could be the first step in a lateral movement attack.
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 SOC analyst notices unusual lateral movement in the network at 2 AM. The IR playbook dictates: identify and contain (isolate the affected machine), then eradicate (remove the malware), then recover (restore from backup), then document. Skipping containment before eradication risks the attacker regaining access. Questions like this test the sequence and rationale of incident response phases.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CISSP question in full detail.
Security Assessment and Testing — This question tests Security Assessment and Testing — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Investigate the successful login — The correct answer is C because a successful login immediately following multiple failed attempts from the same IP address is a classic indicator of a brute-force or password-spraying attack that succeeded. The analyst must investigate the successful login to determine if it was legitimate or an account compromise, checking for anomalous behavior, time of access, and any subsequent actions. Ignoring or prematurely blocking the IP could destroy forensic evidence or lock out a legitimate user, while disabling the account without investigation may be premature if the login was authorized.
What should I do if I get this CISSP question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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