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Over a dozen Democratic groups were approached with ransom demands by Russian hackers over protester funding information , according to a Monday report from Bloomberg .
 ( ransom: ransom demands,  a dozen Democratic groups: victim, Russian hackers: 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: ransom demands,  a dozen Democratic groups: victim, Russian hackers: attacker) 