3451
According to FireEye , APT28 has exploited a number of known security flaws in the past including previously undiscovered " zero day " vulnerabilities in Adobe Flash Player , Java , and Windows .
 ( discover vulnerability: has exploited,  a number of known security flaws: vulnerability, APT28: discoverer, previously undiscovered " zero day " vulnerabilities: vulnerability, Adobe Flash Player: vulnerable system, Java: vulnerable system, Windows: 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:
 ( discover vulnerability: has exploited,  a number of known security flaws: vulnerability, APT28: discoverer, previously undiscovered " zero day " vulnerabilities: vulnerability, Adobe Flash Player: vulnerable system, Java: vulnerable system, Windows: vulnerable system) 