3405
— Frederic Jacobs ( @FredericJacobs ) January 13 , 2017 Jacobs and other security researchers explain the “ backdoor ” is a feature designed to allow WhatsApp users who obtain a new phone to reinstall the WhatsApp app and continue a preexisting conversation thread .
 ( discover vulnerability: explain,  the “ backdoor ”: vulnerability, Jacobs: discoverer, security researchers: 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: explain,  the “ backdoor ”: vulnerability, Jacobs: discoverer, security researchers: discoverer) 