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In the past , denial of service attacks have been perpetrated by customers with a grudge or by blackmailers , but there is no indication from Lloyds that a ransom demand was received .
 ( ransom: a ransom demand,  denial of service attacks have been perpetrated: attack pattern, Lloyds: victim, blackmailers: attacker, customers: attacker) 
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: a ransom demand,  denial of service attacks have been perpetrated: attack pattern, Lloyds: victim, blackmailers: attacker, customers: attacker) 