2470
Yahoo ’s board has blamed unnamed senior executives and its legal team for failing to properly investigate a 2014 security incident which saw 500 million user accounts stolen by state - sponsored attackers .
 ( data breach: a 2014 security incident, None) 
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: a 2014 security incident, None) 