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Next Step After Ransomware Containment: Create Forensic Image
After detecting a ransomware infection on a file server, the incident response team performs containment and eradication. Which step should be prioritized during the recovery phase to minimize business impact?
⚠ Common exam trap
CISM often tests the distinction between recovery and eradication phases; candidates may incorrectly choose patching or reimaging as the first recovery step, but the priority is restoring operations from clean backups.
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 data from verified clean backups
The recovery phase of incident response focuses on restoring systems and data to normal operations. Restoring from verified clean backups is the most reliable way to recover encrypted data without paying a ransom or introducing further risk. It directly minimizes business impact by enabling the fastest return to service, provided the backups are free of malware and recent enough to meet recovery objectives. Patching and reimaging are important but belong to eradication and hardening, not immediate recovery.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Contact the attackers to negotiate a decryption key
Why it's wrong here
Negotiating with attackers funds criminal activity, provides no guarantee of decryption, and may violate law or policy. Engagement would only be contemplated under sanctioned law-enforcement direction, not as a recovery step prioritised to minimise business impact.
- ✗
Reimage all servers in the same network segment
Why it's wrong here
Reimaging every server in the segment destroys unaffected systems and lengthens outage, worsening business impact. Reimaging is warranted for hosts confirmed compromised by the same malware, not as a blanket recovery action across a network segment.
- ✗
Identify and patch the vulnerability used for entry
Why it's wrong here
Patching the entry vulnerability is eradication work, already completed before recovery begins; recovery prioritises restoring the file server from clean backups and validating data integrity to resume business operations. Vulnerability remediation is tempting because it prevents reinfection, and would be correct during the eradication or post-incident improvement phase.
- ✓
Restore data from verified clean backups
Why this is correct
Restoring from verified clean backups returns the file server to a known-good state, directly minimising downtime and data loss after containment and eradication. Backups must be validated as free of the ransomware, otherwise reinfection occurs, so verification is integral to this recovery priority.
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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 ISACA exam blueprint
This CISM practice question is part of Courseiva's free ISACA 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 CISM exam.