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I 'm just surprised that online bank thieves took so long in joining spying contractors in abusing the global SS7 network , " Karsten Nohl , a cybersecurity researcher who has highlighted vulnerabilities in SS7 , told Motherboard in an email .
 ( discover vulnerability: has highlighted,  SS7: vulnerable system, vulnerabilities: vulnerability, Karsten Nohl: discoverer, cybersecurity researcher: discoverer, abusing the global SS7 network: capabilities) 
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 highlighted,  SS7: vulnerable system, vulnerabilities: vulnerability, Karsten Nohl: discoverer, cybersecurity researcher: discoverer, abusing the global SS7 network: capabilities) 