CAS-004 Security Operations Practice Question
An organization is unable to patch a critical vulnerability in a legacy application due to vendor limitations. The risk assessment indicates a high likelihood of exploitation. Which compensating control should the organization implement to reduce the risk?
⚠ Common exam trap
The trap is selecting a control that only detects or monitors (like scanning) rather than one that actually reduces risk; candidates must distinguish between detection and prevention controls.
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 network segmentation to isolate the application
Network segmentation isolates the legacy application from critical systems, limiting the blast radius if the vulnerability is exploited. This compensating control reduces risk by preventing lateral movement and restricting access to the vulnerable application, even though the vulnerability remains unpatched.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Deploy an additional firewall in front of the application
Why it's wrong here
An extra firewall filters network traffic but cannot block exploitation occurring through the application's own permitted input paths, such as crafted requests over allowed ports. It is tempting because firewalls are classic compensating controls, yet they would be correct only where the vulnerability is reachable solely via traffic a firewall can distinguish.
- ✗
Disable the application until a patch is available
Why it's wrong here
Disabling the application removes the risk but also removes the business capability, which is not a compensating control that preserves operation. It is tempting because it guarantees no exploitation, yet it would be correct only if the application were non-essential or a temporary outage acceptable.
- ✗
Increase the frequency of vulnerability scanning
Why it's wrong here
Scanning detects and reports the vulnerability but does not reduce the likelihood of exploitation, since detection is not prevention. It is tempting because scanning is a recognised risk-management activity, yet it would be correct only for improving visibility, not for mitigating an actively exploitable flaw.
- ✓
Implement network segmentation to isolate the application
Why this is correct
Network segmentation places the unpatched legacy application in an isolated segment with restricted inbound and outbound traffic, limiting lateral movement and reducing exploitability. This compensates for the vendor-imposed inability to patch while addressing the high likelihood of exploitation.
Quick reference
AAA Protocol Comparison
| Protocol | Port(s) | Encryption | Transport | Primary Use |
|---|---|---|---|---|
| RADIUS | 1812 / 1813 | Password only | UDP | Network access control |
| TACACS+ | 49 | Full packet | TCP | Device administration |
| Diameter | 3868 | Full session | TCP / SCTP | Carrier / mobile networks |
| 802.1X | — | EAP-based | Layer 2 | Port-based access control |
TACACS+ encrypts the entire packet; RADIUS only encrypts the password field — a key exam distinction.
Go deeper
Related to this question
About these practice questions
One of 973 original CAS-005 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CompTIA exam blueprint
This CAS-005 practice question is part of Courseiva's free CompTIA 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 CAS-005 exam.