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For instance , in December 2014 , Yahoo 's security team knew the state - sponsored actor had stolen copies of backup files that contained users ' personal data .
 ( data breach: had stolen,  the state - sponsored actor: attacker, copies of backup files: compromised data, users ' personal data: compromised data, December 2014: time) 
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:
 ( data breach: had stolen,  the state - sponsored actor: attacker, copies of backup files: compromised data, users ' personal data: compromised data, December 2014: time) 