The theft, which took place in December, became public Friday after it became known that law enforcement had searched the servers of a Swedish software consulting company for evidence of the crime.
"Because one of our government customers was a target of this cybercrime, we are working closely with them, as well as domestic law enforcement and international organizations to remedy the breach in security," B.R. Smedley, CEO of Exigent, said in a statement.
Exigent's software, known as OS/COMET, allows ground-control personnel to communicate and send commands to satellites and rockets. The Melbourne, Fla.-based company stated that the source code of the version that had been stolen was "older," not the newest version released last April.
Swedish law enforcement searched the servers of software consultant Carbonide on Feb. 6 on suspicion that a hacker used the company's Freebox Web e-mail service to distribute the source code to others, said Erik Wickbom, CEO of Stockholm, Sweden-based Carbonide.
"We didn't know it was there, and we didn't know it was source code," he told CNET News.com on Friday. Although the search occurred nearly a month ago, it did not become public until Friday.
After the four-hour search, the team of Swedish law enforcement and FBI computer experts left with copies of the evidence.
"Immediately after, we deleted the source code," Wickbom said.
The stolen source code is a fragment of the complete application. Wickbom said that's because law enforcement officials could fit the data on a single floppy disk, about 1.44MB of space.
Although the hacker used the name "Leeif" on the system, Wickbom said, the account was stolen. Wickbom added that the trail points to a German university as the source of the intrusion into the Freebox network but that a skilled attacker could easily have broken in from elsewhere.
"He knew what he was doing, absolutely," Wickbom said.
Wickbom did not name the German school, but Exigent filed a suit against both Carbonide and the University of Kaiserlautern in Germany on Jan. 19 in connection with the case.
The U.S. Air Force has plans to use the OS/COMET software to control the NAVSTAR Global Positioning System from its Colorado Springs Monitor Station, which is part of the Air Force Space Command, according to a December press release from the software's creator, Exigent Software Technology, a subsidiary of Exigent International. Exigent valued the deal at $2.7 million.
Although Exigent did not name the government customer, a Reuters report indicated that the source code had been stolen from the U.S. Naval Research Laboratory in Washington, D.C., on Dec. 24. The military detected the intrusion three days later.
In reaction to the theft, Exigent said, it requested that the government system run a "lock-up" procedure.
The FBI would not comment on the theft or the investigation.