San Francisco Municipal Transportation System (Muni) has been reportedly hit by hackers using ransomware, forcing the agency to close its light-rail ticketing machines and point-of-payment systems on the network.
All computers across the city’s transport network were disabled with screens displaying a message from the hackers, which read 'You Hacked, ALL Data Encrypted. Contact For Key'.
The hackers have demanded a ransom of 100 Bitcoins.
An HDDCrypto ransomware attack can allow a hacker to lock-out a system from its owners.
Following the attack, Muni passengers were allowed to ride for free.
Muni said it could not discover the extent of damage caused, or whether any employee or passenger data had been breached.
The operator is also concerned whether the Clipper smart-card system was also breached.
Clipper cards are used by Muni for transit payments and used for around 800,000 fare payments a day.
Muni spokesman Paul Rose told the San Francisco Chronicle: “At this point, there are not any indications of any impacts to customers.
“We’re doing a full investigation to find out exactly what we are dealing with.”
Ticketing machines have since been placed online again. However, it is still unclear whether the attack has been contained and the identity of the hackers has been confirmed.