1583
F5 experts say that in the beginning , attackers targeted Struts instances running on Linux servers , where they would end up installing the PowerBot malware , an IRC - controlled DDoS bot also known as PerlBot or Shellbot .
 ( discover vulnerability: say,  F5 experts: discoverer, Struts: vulnerable system, Linux servers: supported platform) 
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: say,  F5 experts: discoverer, Struts: vulnerable system, Linux servers: supported platform) 