hardMultiple ChoiceObjective-mapped
CAS-004 Practice Question: A global e-commerce company processes payment…
A global e-commerce company processes payment card data and is required to comply with PCI DSS. During a quarterly vulnerability scan, the security team discovers that a web application firewall (WAF) rule is blocking legitimate traffic, causing transaction failures. The WAF is a critical compensating control for a known vulnerability in the application that cannot be patched for 90 days. The compliance officer is concerned about maintaining PCI DSS compliance while ensuring business continuity. The security team proposes temporarily disabling the WAF to restore service while they fine-tune the rules. Which of the following is the BEST action?
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
✓
Temporarily modify the WAF rule set to allow legitimate traffic while maintaining security, and schedule a permanent fix within 24 hours.
The best action because temporarily modifying the WAF rule set to allow legitimate traffic while maintaining security addresses both business continuity and PCI DSS compliance. The WAF serves as a critical compensating control for a known vulnerability that cannot be patched for 90 days; disabling it (as in Option B) would remove this control, likely violating PCI DSS Requirement 6.6 and increasing risk. Option A (segmentation) may not provide equivalent protection and could be impractical in the short term. Option C (accepting transaction failures) harms business operations without a long-term benefit. Fine-tuning rules and scheduling a permanent fix within 24 hours balances security and availability, keeping the compensating control active.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Segment the affected application from the rest of the network and remove the WAF from the data path.
Why it's wrong here
Network segmentation alone may not satisfy PCI DSS requirements for a compensating control.
- ✗
Disable the WAF immediately to restore service and document the decision as a risk acceptance.
Why it's wrong here
Disabling the WAF removes the compensating control, likely violating PCI DSS.
- ✗
Accept the risk of transaction failures and keep the WAF in place until the rules are fully tested.
Why it's wrong here
Accepting transaction failures is not acceptable for business continuity.
- ✓
Temporarily modify the WAF rule set to allow legitimate traffic while maintaining security, and schedule a permanent fix within 24 hours.
Why this is correct
Fine-tuning rules restores service without compromising the compensating control.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.