Ransomware is a form of malware, and a particular type of Trojan horses programs. The malware encrypts or blocks data or even entire computer systems, so the user can no longer access it. To re-gain access via a private key the user needs to pay a ransom to a generally foreign bank account which is not traceable. In 2015 / 2016 several hospitals have fallen victim to ransomware attacks. In Los Angeles, a hospital was unable to operate for more than a week. Also, paying the ransom does not necessarily guarantee the provision of the private key by the cybercriminal.