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In one situation , a user paid a ransom to their attackers , but their attackers could not decipher the files encrypted by their own Trojan.Encoder ( Cryptolocker ) , and advised the user to seek help … from Doctor Web 's technical support service , " the webpage reads .
 ( ransom: paid a ransom,  their attackers: attacker, a user: 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: paid a ransom,  their attackers: attacker, a user: victim) 