hardMultiple Choice
CAS-004 Practice Question: During a ransomware incident, the organization…
During a ransomware incident, the organization discovers that all production backups have been encrypted by the attacker. What is the most effective recovery approach?
⚠ Common exam trap
CAS-005 often tests the effectiveness of different recovery methods, and candidates may incorrectly choose paying the ransom or using decryption tools due to desperation or lack of awareness of immutable backup capabilities.
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
✓
Restore from offline immutable backups
Restoring from offline immutable backups is the most effective recovery approach when production backups have been encrypted by ransomware. Immutable backups cannot be altered or deleted, even by an attacker with administrative credentials, ensuring that a clean copy of data is available for restoration. This approach minimizes downtime and avoids paying the ransom.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Restore from offline immutable backups
Why this is correct
Offline immutable backups cannot be encrypted or deleted by ransomware because they are not reachable from the production network. Restoring from them recovers clean data without paying, directly addressing the stem's constraint that all production backups were encrypted.
- ✗
Restore from system restore points
Why it's wrong here
System restore points capture only OS configuration and registry state on Windows endpoints, not production data volumes, so they cannot recover encrypted backups. They are tempting because they are a built-in rollback mechanism, but they are correct for reversing a bad driver or update, not a ransomware data-loss event.
- ✗
Use a decryption tool from security vendors
Why it's wrong here
Vendor decryption tools only work for known ransomware families with published keys; encrypted production backups cannot be reliably restored this way, and paying or guessing risks further loss. Tempting because free decryptors exist for some strains, but they are the right choice only for confirmed, decryptable variants, not destroyed backups.
- ✗
Pay the ransom to obtain the decryption key
Why it's wrong here
Paying the ransom funds criminals and offers no guaranteed decryption key, so recovery remains uncertain and may breach sanctions law. It is tempting because it appears to be the only route once backups are gone, yet it addresses attacker economics rather than restoring data from an isolated, immutable copy.
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About these practice questions
Courseiva writes every CAS-005 question from scratch — 973 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. 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.