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Hackers who launch such attacks lock their targets out of their data in an effort to extract a ransom for its return .
 ( ransom: ransom,  Hackers: attacker, lock their targets out of their data: attack pattern) 
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,  Hackers: attacker, lock their targets out of their data: attack pattern) 