3293
De Ceukelaire has discovered that he can exploit Facebook to obtain cell phone numbers of users ; which they want to remain hidden .
 ( discover vulnerability: has discovered,  Facebook: vulnerable system, obtain cell phone numbers of users: capabilities, De Ceukelaire: discoverer) 
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 discovered,  Facebook: vulnerable system, obtain cell phone numbers of users: capabilities, De Ceukelaire: discoverer) 