552
The bug , patched in March 2017 , targeted the SMB ( Server Message Block ) , experts found .
 ( patch vulnerability: patched,  bug: vulnerability, March 2017: time, Server Message Block: vulnerable system, the SMB: vulnerable system) 
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:
 ( patch vulnerability: patched,  bug: vulnerability, March 2017: time, Server Message Block: vulnerable system, the SMB: vulnerable system) 