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CISM Practice Question: A multinational corporation has just detected a…
A multinational corporation has just detected a ransomware attack that encrypted critical files on a file server. The incident response team has been activated. Which of the following should be the FIRST action taken by the team?
⚠ Common exam trap
Candidates often choose 'Restore from backup' first because it seems like a direct fix, but CISM emphasizes containment before eradication or recovery to limit damage and preserve forensic integrity.
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
✓
Isolate the affected systems from the network
The first priority in ransomware incident response is containment to prevent the encryption from spreading to other systems. Isolating the affected file server from the network (e.g., disabling the network interface or disconnecting the cable) stops the ransomware from communicating with its command-and-control server and encrypting additional shares. This aligns with the NIST SP 800-61 containment strategy and ensures that the incident response team can safely preserve forensic evidence before any remediation.
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 encrypted files from backup
Why it's wrong here
Restoration should occur after containment and forensic analysis.
- ✗
Reboot the file server to clear the encryption
Why it's wrong here
Rebooting may lose volatile evidence and does not remove encryption.
- ✓
Isolate the affected systems from the network
Why this is correct
Isolation stops the ransomware from spreading and limits damage.
- ✗
Notify law enforcement
Why it's wrong here
Notifying law enforcement is important but not the first step; containment is priority.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.