hardMultiple ChoiceObjective-mapped
CAS-004 Practice Question: A company that processes credit card transactions…
A company that processes credit card transactions discovers that a third-party vendor with access to its network has suffered a data breach. The vendor's access was limited but included a connection to the cardholder data environment. The company must comply with PCI DSS. Which of the following is the FIRST action the company should take?
⚠ Common exam trap
A common mix-up: candidates choose forensic investigation (Option C) first, thinking they need to understand the full scope before acting, but PCI DSS and incident response best practices mandate immediate containment (revoke access) to stop the bleeding before any analysis begins.
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
✓
Revoke the vendor's access immediately and change all shared credentials.
Under PCI DSS Requirement 7 and 12, the company must immediately contain the breach by revoking the third-party vendor's access and changing all shared credentials. This is the first action because it stops further unauthorized access to the cardholder data environment (CDE) and prevents the attacker from using compromised credentials to pivot or exfiltrate data. Delaying containment could expand the breach scope and increase compliance penalties.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Revoke the vendor's access immediately and change all shared credentials.
Why this is correct
Immediate containment is the first priority to stop further exfiltration.
- ✗
Notify all affected cardholders as required by law.
Why it's wrong here
Notification is a later step after determining scope and legal obligations.
- ✗
Perform a forensic investigation to determine the scope of the breach.
Why it's wrong here
Forensics should be conducted after the threat is contained.
- ✗
Contact the acquiring bank and report the breach.
Why it's wrong here
Reporting is important but should occur after containment.
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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.