According to a confidential report by the German federal information security agency, BSI, hackers gained access to federal police computers in September 2010 and were able steal information undetected for months, the Bild am Sonntag newspaper reported.
In addition, hackers were able to gain access to the German customs service and publish stolen files on the internet.
The BSI report said that hackers were able to get into the police databases because of cheap software with insufficient security controls, according to the Germany weekly magazine Focus.
According to the magazine, BSI reported that every server of the police's spy program "Patras" had been infiltrated by hackers. Patras is used to locate serious criminals and terrorist suspects by gathering information from GPS systems in cars and mobile phones. It is used by both state and federal police forces, as well as Germany's customs officers.
Following the cyberattack, all of the relevant servers had to be shut down to prevent more data from being stolen.
The breach could lead to hundreds of confidential police investigations appearing on the internet. "That is pretty much the worst thing that could happen," an anonymous security officer told the magazine.