The answer is to add a WAF rule to block common SQL injection payloads and signatures. This is the correct immediate control because it provides a virtual patch at the application layer, preventing malicious input from reaching the database without requiring code changes. While parameterized queries are the definitive long-term fix, the WAF rule minimizes performance impact and maintains defense in depth by stopping attacks at the perimeter, buying time for the development team to address legacy dependencies. On the CompTIA SecurityX CAS-004 exam, this scenario tests your ability to balance security controls with operational constraints—a common trap is choosing a detection-only solution like increasing IDS sensitivity, which fails to prevent the exploit. The key distinction is that WAF rules block, while IDS only alerts. Memory tip: Think "WAF first, code fix later"—the WAF is your emergency patch, not the permanent repair.
CAS-004 Security Architecture Practice Question
This CAS-004 practice question tests your understanding of security architecture. 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 architect is reviewing the architecture of a critical web application that handles sensitive financial transactions. The application is deployed across three tiers: a web server, an application server, and a database server. The application is protected by a web application firewall (WAF) and a network-based intrusion detection system (IDS). Recent penetration testing identified a SQL injection vulnerability in the application's search feature. The architect needs to propose a remediation that minimizes performance impact and maintains defense in depth. The development team is slow to fix code due to legacy dependencies. What should the security architect recommend as the MOST effective immediate control?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Add a WAF rule to block common SQL injection payloads and signatures.
Option D (Implement parameterized queries in the application code) is the most effective long-term fix, but since the development team is slow, the best immediate control is to add a WAF rule to block SQL injection patterns. Option A (Disable the search feature) is too disruptive. Option B (Increase IDS sensitivity) would only detect, not prevent. Option C (Segment the database server) is good but does not address the vulnerability at the application layer.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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 search feature until the code is fixed.
Why it's wrong here
Disabling a feature impacts business functionality and is not a balanced control.
✗
Isolate the database server on a separate network segment with strict firewall rules.
Why it's wrong here
Segmentation reduces lateral movement but does not prevent exploitation of the vulnerability.
✓
Add a WAF rule to block common SQL injection payloads and signatures.
Why this is correct
A WAF can provide virtual patching to mitigate the vulnerability until code fix is deployed.
Related concept
Static NAT maps one inside address to one outside address.
✗
Increase the IDS sensitivity to detect SQL injection attempts and automatically block them.
Why it's wrong here
IDS is detection-only; it cannot prevent the attack from reaching the database.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
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
Got this wrong? Here's your next step.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related CAS-004 NAT questions on configuration and troubleshooting.
Security Architecture — This question tests Security Architecture — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Add a WAF rule to block common SQL injection payloads and signatures. — Option D (Implement parameterized queries in the application code) is the most effective long-term fix, but since the development team is slow, the best immediate control is to add a WAF rule to block SQL injection patterns. Option A (Disable the search feature) is too disruptive. Option B (Increase IDS sensitivity) would only detect, not prevent. Option C (Segment the database server) is good but does not address the vulnerability at the application layer.
What should I do if I get this CAS-004 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related CAS-004 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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Question Discussion
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