According to TechFlow, the operator of Seattle-Tacoma International Airport faced a serious cybersecurity threat on September 19. Airport management official Lance Lyttle reported to the U.S. Senate Committee that the hacker group Rhysida demanded 100 bitcoins (about 6 million U.S. dollars) as a ransom in exchange for stolen files.

Lyttle said the hackers had published eight stolen files on the dark web, but did not disclose the specific contents. The airport decided not to pay the ransom, believing it was not in the interest of taxpayers. The FBI is conducting a criminal investigation.

The attack began on August 24, during the busy period before the Labor Day holiday. Although flight operations were not affected, ticketing, check-in and baggage handling systems were disrupted. Small airlines were forced to use paper boarding passes.

Lyttle said the airport appears to have successfully blocked the attack, but some data was encrypted. The airport will contact individuals who may have been affected. The Rhysida hacker group was also suspected of attacking the systems of the city of Columbus, Ohio last month.