Twitter Races to Unravel How Cyber-Attack Came From Inside

As Twitter Inc. grapples with the worst security breach in its 14-year history, it must now uncover whether its employees were victims of sophisticated phishing schemes or if they deliberately allowed hackers to access high-profile accounts.

On Wednesday, some of the world’s most prominent people, including former President Barack Obama and Democratic presidential candidate Joe Biden, along with Bill Gates, Elon Musk and Warren Buffett, had their Twitter accounts post invitations for an apparent Bitcoin scam. Twitter reacted by blocking further posts from all verified accounts on the service and said it had detected “a coordinated social engineering attack by people who successfully targeted some of our employees with access to internal systems and tools.”

The company’s explanation has ignited speculation over the identity of the perpetrators and what they were actually targeting in the attack.