Twitter’s former security chief has told US Congress there was “at least one agent” from China’s intelligence service on the social network’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. Mr Zatko told legislators that the platform is plagued by weak cyber defences that make it vulnerable to exploitation by “teenagers, thieves and spies” and put the privacy of users at risk. “I am here today because Twitter leadership is misleading the public, lawmakers, regulators and even its own board of...