Inside the FBI hack: Agents fearful and angry after 'dangerous' data breach

Current and former FBI agents have spoken to BBC News of their shock, fear and anger following a hack that appears to have exposed the private and personal information of the agency's entire workforce.

"This is really bad for our undercover agents," says one former FBI agent, who fears for the safety of his colleagues.

The former cyber investigator is in a group chat with current agents who are worried their personal information could soon be freely available online to criminals and hostile nation-state hackers.

He says staff fear they could be targeted, or that criminals could use the data to create highly convincing phishing attempts, scams or demands for bribes.

The hacking group ShinyHunters is threatening to publish the stolen databases and documents within four days unless its demands are met.

Some agents are also concerned about the risk of physical attacks from cyber criminals they have investigated.

"One of the things we are discussing in the group chat is 'violence-as-a-service' attacks from young online gangs," says the former worker .

"They could use this information to harass an FBI agent who has worked on their cases."