Shares in Capita PLC (LSE:CPI) slumped 7% after reports suggested the recent cyber attack was far more serious than the company has admitted.
The Sunday Times said personal bank account details, addresses and passport photos are now being leaked online, having apparently been stolen by the hacking group Black Basta.
Capita, which has £6.5bn in government contracts — including for the NHS, the army and the Cabinet Office — handles the personal details of millions of members of the public.
It admitted it had been infiltrated earlier this month but stressed that people’s personal details had remained secure.
However, security experts showed The Sunday Times how pages of details apparently obtained from Capita were being touted for sale on the dark web page of Black Basta.
This trove of information features people’s phone numbers, details of more than 100 bank accounts with sort codes, and home addresses.
The documents appear to be a sample of what was have obtained, as the web page states that anyone wanting access to more can buy it in bitcoin.
The data includes personal details of teachers applying for jobs at schools.
Other information appears to be the bank account details of people and firms supplying Capita with goods or services.