Twitter’s former security chief told Congress Tuesday there was “at least one agent” from China’s intelligence service on Twitter’s payroll and that the company knowingly allowed India to add agents to the company roster as well, potentially giving those nations access to sensitive data about users. These were some of the troubling revelations from Peiter “Mudge” Zatko , a respected cybersecurity expert and Twitter whistleblower who appeared before the Senate Judiciary Committee to lay out his allegations against the company. Zatko told lawmakers that the social media platform is plagued by weak cyber defenses that make it vulnerable to exploitation...