Quick Answer
A spike in failed login attempts to 200 per day, double the established threshold of 100, indicates a brute-force attack in progress. This is correct because a brute-force attack systematically tries numerous username and password combinations, directly causing authentication failure logs to surge. The risk indicator here measures a primary symptom of such an attack, and breaching the threshold signals that existing controls—like account lockout or rate limiting—may be failing or insufficient. On the CRISC exam, this scenario tests your ability to link a risk indicator (failed login spike) to a specific threat event, a core skill in risk response and monitoring. A common trap is to dismiss the spike as a user error or system glitch, but remember: a sustained, doubled baseline is the hallmark of an automated attack, not random mistakes. Memory tip: think "double the trouble" — when failed logins double the threshold, suspect a brute-force attack, not a forgetful user.
This CRISC practice question tests your understanding of risk and control monitoring and reporting. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
An organization has a risk indicator that shows the number of failed login attempts per day. The threshold is 100. Last week, the number spiked to 200 on two days. What does this indicate?
The system is experiencing a denial-of-service attack.
Why wrong: Failed logins are not typical of DoS.
There may be a brute-force attack in progress.
High failed logins suggest password guessing.
The password policy needs to be updated.
Why wrong: Not directly indicated by a spike.
Users have forgotten their passwords.
Why wrong: Could be, but security incident is more critical.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
There may be a brute-force attack in progress.
A spike in failed login attempts from a baseline of 100 to 200 per day is a classic indicator of a brute-force attack, where an attacker systematically tries multiple username/password combinations. This risk indicator directly measures authentication failures, which are the primary symptom of such an attack. The threshold breach signals that the control (account lockout or rate limiting) may be insufficient or failing.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
The system is experiencing a denial-of-service attack.
Why it's wrong here
Failed logins are not typical of DoS.
There may be a brute-force attack in progress.
Why this is correct
High failed logins suggest password guessing.
Related concept
Read the scenario before looking for a memorised answer.
The password policy needs to be updated.
Why it's wrong here
Not directly indicated by a spike.
Users have forgotten their passwords.
Why it's wrong here
Could be, but security incident is more critical.
Common exam traps
The trap here is that candidates confuse a spike in failed logins with a DoS attack, but DoS attacks target availability (e.g., SYN flood) rather than authentication failures, which are a confidentiality/integrity concern.
Detailed technical explanation
Brute-force attacks often use tools like Hydra or Medusa that can generate hundreds of authentication requests per minute, easily exceeding a threshold of 100 per day. Under the hood, the risk indicator should be monitored with a rolling window (e.g., 24-hour sliding window) to detect rapid bursts, as a simple daily count can mask attacks that happen within a few hours. In real-world scenarios, a spike to 200 failed logins might also indicate a credential stuffing attack using leaked password lists, which is a subtype of brute-force.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
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FAQ
Risk and Control Monitoring and Reporting — This question tests Risk and Control Monitoring and Reporting — Read the scenario before looking for a memorised answer..
The correct answer is: There may be a brute-force attack in progress. — A spike in failed login attempts from a baseline of 100 to 200 per day is a classic indicator of a brute-force attack, where an attacker systematically tries multiple username/password combinations. This risk indicator directly measures authentication failures, which are the primary symptom of such an attack. The threshold breach signals that the control (account lockout or rate limiting) may be insufficient or failing.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
This CRISC practice question is part of Courseiva's free ISACA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CRISC exam.
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