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— 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 .
 the “ backdoor ”: vulnerability; Jacobs: discoverer; security researchers: discoverer
Given event type and trigger, please tell me the arguments of all the listed option. Output format is "name1: role1; name2: role2". 
Event type: discover vulnerability 
  Option: vulnerable system owner, vulnerability, capabilities, time, vulnerable system version, discoverer, common vulnerabilities and exposures, supported platform, vulnerable system 
Text: {0} 
Answer:
 the “ backdoor ”: vulnerability; Jacobs: discoverer; security researchers: discoverer