- A
Implement a unidirectional gateway that enforces one-way data flow
A unidirectional gateway prevents external threats from entering the ICS while allowing data export, preserving availability.
- B
Deploy a host-based intrusion detection system on each ICS device
Why wrong: Host-based IDS on legacy devices may not be compatible and could impact performance.
- C
Upgrade the ICS to modern protocols with built-in authentication
Why wrong: Upgrading legacy ICS may be costly and cause downtime, potentially affecting availability.
- D
Disconnect the ICS from the corporate network and use manual data transfer
Why wrong: Manual transfer would eliminate real-time access, reducing operational efficiency.
Question 336 of 1,000
CRISC Information Technology and Security Practice Question
This CRISC practice question tests your understanding of information technology and security. 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.
A power utility is integrating its industrial control system (ICS) with the corporate IT network to enable real-time operational data access. The risk manager identifies that the ICS uses legacy proprietary protocols without authentication. Which risk treatment option best addresses this issue while maintaining operational availability?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Implement a unidirectional gateway that enforces one-way data flow
A unidirectional gateway (data diode) enforces one-way data flow from the ICS to the corporate IT network, preventing any inbound traffic that could exploit the legacy protocols' lack of authentication. This maintains operational availability because the ICS remains isolated from direct network attacks while still providing real-time data access. It is the only option that addresses the authentication gap without disrupting legacy system operations.
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.
- ✓
Implement a unidirectional gateway that enforces one-way data flow
Why this is correct
A unidirectional gateway prevents external threats from entering the ICS while allowing data export, preserving availability.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Deploy a host-based intrusion detection system on each ICS device
Why it's wrong here
Host-based IDS on legacy devices may not be compatible and could impact performance.
- ✗
Upgrade the ICS to modern protocols with built-in authentication
Why it's wrong here
Upgrading legacy ICS may be costly and cause downtime, potentially affecting availability.
- ✗
Disconnect the ICS from the corporate network and use manual data transfer
Why it's wrong here
Manual transfer would eliminate real-time access, reducing operational efficiency.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose upgrading protocols (Option C) as the 'best practice' without considering the operational availability constraints of legacy ICS environments, where a unidirectional gateway provides a non-disruptive security layer.
Detailed technical explanation
How to think about this question
Unidirectional gateways often use optical data diodes that physically prevent electrical signals from traveling in the reverse direction, ensuring no TCP/IP handshake or ACK can traverse back. In power utilities, this is critical because legacy protocols like Modbus RTU or DNP3 lack authentication, so any bidirectional connectivity would allow an attacker to send malicious write commands. Real-world implementations, such as those from Waterfall or Owl Cyber Defense, replicate data via a one-way file transfer or syslog feed, preserving the ICS's air-gap-like security while enabling IT-side analytics.
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 practitioner preparing for the CRISC exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
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.
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FAQ
Questions learners often ask
What does this CRISC question test?
Information Technology and Security — This question tests Information Technology and Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Implement a unidirectional gateway that enforces one-way data flow — A unidirectional gateway (data diode) enforces one-way data flow from the ICS to the corporate IT network, preventing any inbound traffic that could exploit the legacy protocols' lack of authentication. This maintains operational availability because the ICS remains isolated from direct network attacks while still providing real-time data access. It is the only option that addresses the authentication gap without disrupting legacy system operations.
What should I do if I get this CRISC 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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Last reviewed: Jul 4, 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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