ransomware

noun2

1. •
   Malware that holds the data of a computer user for ransom, usually requiring or claiming to require payment to restore access.

   • The amount of money generated by ransomware schemes would appear to be quite small given their lack of popularity and the asking price in ransom notes […] — 2008
2. •
   (disapproving) Software that is released as open source only in exchange for payment.