Quick Answer
The answer is to mitigate by implementing compensating controls. This is the most appropriate risk treatment for unpatched legacy systems because the vulnerabilities cannot be eliminated through patching, yet the system remains critical for operations, ruling out decommissioning or acceptance without action. Compensating controls—such as network segmentation, strict access controls, or an application-layer firewall—reduce the likelihood or impact of exploitation without modifying the vulnerable system itself, directly addressing the legacy system risk treatment challenge. On the CRISC exam, this scenario tests your ability to distinguish between risk treatment options when technical constraints and business criticality collide; a common trap is choosing “accept” because the system cannot be patched, but remember that compensating controls are a form of mitigation, not acceptance. Memory tip: “If you can’t patch it, segment and guard it.”
This CRISC practice question tests your understanding of it risk assessment. 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.
During a risk assessment, the risk team identifies that a legacy system has multiple known vulnerabilities that cannot be patched. The system is critical for operations. Which of the following risk treatment options is MOST appropriate?
Accept the risk and monitor
Why wrong: May be insufficient if risk exceeds appetite.
Remediate by applying patches from the vendor
Why wrong: Patching is not possible as vulnerabilities cannot be patched.
Avoid the risk by decommissioning the system
Why wrong: May not be feasible for critical operations.
Mitigate by implementing compensating controls
Reduces risk while preserving system functionality.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Mitigate by implementing compensating controls
Since the legacy system cannot be patched (Option B is impossible) and is critical for operations (decommissioning would disrupt the business, making Option C too drastic), the most appropriate treatment is to implement compensating controls. These controls, such as network segmentation, strict access controls, or an application-layer firewall, reduce the likelihood or impact of exploitation without modifying the vulnerable system itself, aligning with the risk mitigation strategy.
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.
Accept the risk and monitor
Why it's wrong here
May be insufficient if risk exceeds appetite.
Remediate by applying patches from the vendor
Why it's wrong here
Patching is not possible as vulnerabilities cannot be patched.
Avoid the risk by decommissioning the system
Why it's wrong here
May not be feasible for critical operations.
Mitigate by implementing compensating controls
Why this is correct
Reduces risk while preserving system functionality.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates often choose 'Accept the risk and monitor' (Option A) because they confuse 'acceptance' with a valid risk response for unpatched systems, failing to recognize that acceptance requires a formal decision and compensating controls when vulnerabilities are known and exploitable on critical assets.
Detailed technical explanation
Compensating controls for legacy systems often involve network segmentation using VLANs or firewall rules (e.g., restricting inbound/outbound traffic to only necessary ports/protocols), implementing a Web Application Firewall (WAF) to filter malicious payloads, or deploying host-based intrusion detection (HIDS) to monitor for exploitation attempts. In a real-world scenario, a bank might isolate an unpatched mainframe on a separate subnet with strict ACLs and require jump-host access for administrators, effectively reducing the attack surface without touching the legacy code.
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
IT Risk Assessment — This question tests IT Risk Assessment — Read the scenario before looking for a memorised answer..
The correct answer is: Mitigate by implementing compensating controls — Since the legacy system cannot be patched (Option B is impossible) and is critical for operations (decommissioning would disrupt the business, making Option C too drastic), the most appropriate treatment is to implement compensating controls. These controls, such as network segmentation, strict access controls, or an application-layer firewall, reduce the likelihood or impact of exploitation without modifying the vulnerable system itself, aligning with the risk mitigation strategy.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. During a risk assessment, a risk practitioner identifies that a legacy application uses a deprecated encryption protocol. The application is critical for business operations and cannot be patched. Which of the following is the BEST approach to assess the risk?
mediumWhy B: The best approach is to consider the compensating controls in place. The risk should be evaluated in context of existing controls; if controls reduce likelihood/impact, residual risk may be acceptable. Option A is too extreme without analysis; option B is not a complete assessment; option D is premature.
Last reviewed: Jun 25, 2026
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