Report: US air-traffic control systems hacked

In February, hackers compromised an FAA public-facing computer and used it to gain access to personally identifiable information, such as Social Security numbers, on 48,000 current and former FAA employees, the report said.

Last year, hackers took control of FAA critical network servers and could have shut them down, which would have seriously disrupted the agency's mission-support network, the report said. Hackers took over FAA computers in Alaska, becoming "insiders," according to the report dated Monday.

Then, taking advantage of interconnected networks, hackers later stole an administrator's password in Oklahoma, installed "malicious codes" with the stolen password and compromised the FAA domain controller in the Western Pacific Region, giving them the access to more than 40,000 FAA user IDs, passwords, and other data used to control a portion of the mission-support network, the report said.

And in 2006, a virus spread to the air traffic control (ATC) systems, forcing the FAA to shut down a portion of its systems in Alaska, according to the report.

The attacks so far have primarily disrupted mission-support functions, but attacks could spread over network connections from those areas to the operational networks where real-time surveillance, communications and flight information is processed, the report warned.

"In our opinion, unless effective action is taken quickly, it is likely to be a matter of when, not if, ATC systems encounter attacks that do serious harm to ATC operations," the report concluded.

This article was originally posted on CNET News.