hardMultiple ChoiceObjective-mapped
CAS-004 Practice Question: A financial institution manages customer data…
A financial institution manages customer data through a web application built on a LAMP stack. The application uses a third-party library for PDF generation that was patched last year. Recently, the security team discovered that an attacker exploited an unpatched vulnerability in the library to execute arbitrary code on the server. The library vendor has released an update, but the development team is concerned that updating the library will break several custom features that rely on its internal API. The CIO wants to minimize risk while maintaining business continuity. The application is critical to daily operations, and any downtime would result in significant revenue loss. Which course of action should the security analyst recommend?
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 web application firewall (WAF) with a custom rule to block known attack patterns against the library, and then schedule the patch for the next maintenance window
Deploying a WAF with custom rules provides virtual patching, reducing risk immediately while allowing time for thorough testing of the library update. Option A (immediate patch) could break features without adequate testing. Option B (VPN) does not address the vulnerability. Option D (disable PDF generation) removes functionality, impacting business operations.
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 PDF generation feature entirely until the library can be updated in the next quarterly release
Why it's wrong here
Disabling the feature impacts business operations and may not be acceptable.
- ✗
Deploy a virtual private network (VPN) for all access to the server and restrict input to only trusted IPs
Why it's wrong here
VPN does not prevent exploitation of the library vulnerability.
- ✓
Implement a web application firewall (WAF) with a custom rule to block known attack patterns against the library, and then schedule the patch for the next maintenance window
Why this is correct
WAF provides virtual patching to block exploits while the team tests the update.
- ✗
Immediately apply the vendor's patch and then test all features in a staging environment for a month before production rollout
Why it's wrong here
Immediate patching risks breaking production features; testing for a month delays protection.
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JA
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.