"This is a form of digital extortion, " said the BKA in its alert about the virus.

BBC: Ransomware page

The warning about the novel strain of ransomware was issued by Germany's Federal Criminal police office (the Bundeskriminalamt or BKA).

BBC: Ransomware page

The ransomware version found by the BKA uses a pop-up window that says the machine has been locked down due to "unauthorised network activity".

BBC: Ransomware page

The FBI had passed the request for the search -- along with names of the people connected to the apartment -- to its German counterpart, the BKA, the federal criminal agency.

CNN: FBI request German flat raid

Germany's BKA said users should not pay the fine "under any circumstances" and added that neither the BKI or GVU collected cash in this way from those suspected of viewing illegal images or pirating content.

BBC: Ransomware page