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Cybersecurity experts say the unknown hackers who launched the “ ransomware ” attacks used a hole in Microsoft software that was discovered by the National Security Agency and exposed when NSA documents were leaked online .
 ( ransom: “ ransomware ” attacks,  hackers: attacker, Microsoft software: victim, used a hole: attack pattern) 
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: “ ransomware ” attacks,  hackers: attacker, Microsoft software: victim, used a hole: attack pattern) 