1638
According to the organization , no confidential information was lost or destroyed , including PHI , and the practice group never received a ransom demand or other communications from unknown persons .
 ( ransom: ransom demand,  unknown persons: attacker, the practice group: victim) 
Locate the role in the text that participated in the event based on the event type and return it in the event list. 
 Option: Event type: phishing, data breach, ransom, discover vulnerability, patch vulnerability, Arguments type: vulnerable system, capabilities, vulnerability, number of victim, issues addressed, compromised data, damage amount, common vulnerabilities and exposures, victim, patch number, number of data, tool, discoverer, time, purpose, place, payment method, releaser, vulnerable system version, attacker, supported platform, patch, price, vulnerable system owner, trusted entity, attack pattern. 
Text: {0} 
Answer:
 ( ransom: ransom demand,  unknown persons: attacker, the practice group: victim) 