US government contractor Exigent Software Technology has admitted that unidentified hackers broke into a restricted military computer system and stole the source codes controlling satellite and missile guidance systems.

Hackers got away with two thirds of the code when the target computer at the Naval Research Lab in Washington was attacked on Christmas Eve. The military detected the break-in three days later.

The theft was made public when Swedish police searched the servers of internet service provider Carbonide on suspicion that hackers used the company's Freebox Web email service to distribute the code to others.

Carbonide chief executive Eric Wickborn said: "We didn't know it was there, and we didn't know it was source code. Immediately after the search we deleted the code." He added that law enforcement officials could fit the data onto a single floppy disk.

Wickborn said that although the hacker used the name 'Leeif' on the system, the account was stolen. Carbonide was able to trace the attack on its network to a server at the University of Kaiserslautern in Germany.

The German federal office for criminal affairs said that an investigation is underway. Kaiserslautern is home to several US military installations, including Ramstein Air Force Base.

Exigent developed the OS/Comet program for the US Air Force which uses it on the Navstar Global Positioning System at the Colorado Springs Monitor Station, part of the Air Force Space Command.

The FBI downplayed the attack, however, saying the software was unclassified. Spokesman Chris Murray said the code was secret when first used but is now available commercially.

Also published in Network News