It has also been claimed our four nuclear submarines have also used a system based on the out-of-date software.
Our biggest police force could be wide open to the kind of hack that crippled the NHS.
Met chiefs, who have warned staff against opening “suspicious emails” admitted using what critics say is a “dangerously out-of-date system”.
But they insisted they had “a number of layers of industry-leading security, which we have been monitoring over the past 24 hours”.
Our revelation comes as Home Secretary Amber Rudd said 48 of the 248 NHS England trusts were hit and six are still not running as normal.
Health Secretary Jeremy Hunt has been accused of failing to protect patients and snubbing warnings on vulnerability.
Shadow health secretary Jonathan Ashworth said: “The attack is unprecedented in scale but it is clear our NHS should have been better prepared.”