2703
For example , the 2016 Valentine ’s Day DDoS attacks used Shellshock , a critical vulnerability that ’s present in Linux , UNIX and Mac OS X that had been discovered more than a year earlier .
 ( discover vulnerability: present in,  a critical vulnerability: vulnerability, Linux: vulnerable system, UNIX: vulnerable system, Mac OS X: vulnerable system, Shellshock: vulnerability, DDoS attacks: capabilities) 
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:
 ( discover vulnerability: present in,  a critical vulnerability: vulnerability, Linux: vulnerable system, UNIX: vulnerable system, Mac OS X: vulnerable system, Shellshock: vulnerability, DDoS attacks: capabilities) 