A technician sees a file that is requesting payment to a cryptocurrency address. Which of the following should the technician do first?

Quarantining the computer immediately isolates it from the network, preventing the ransomware from encrypting shared drives, spreading to other systems, or exfiltrating data, thus containing the threat. This is a critical initial response to a confirmed malware infection like ransomware to limit damage.

Disabling System Restore is a destructive action that removes potential recovery points and should not be the first step, especially before understanding the full scope of the infection.

Updating antivirus definitions is a proactive measure for prevention or a later step in remediation; it does not address the immediate threat of an active, known infection which requires containment.

Booting to safe mode can be part of remediation to remove malware, but it does not address the immediate need to prevent the ransomware from spreading or continuing its activity on the network.