The very first variants of Cryptolocker ransomware came out in late September 2013. The idea behind it stemmed directly from the FBI Moneypak/Ukash scams that would lock your computer right before you could log into windows and demand ransom to get back into the computer. Except with this family of malware, your files were locked away through encryption
and victims had to pay the ransom to get their files back. The big difference was that you couldn't fix this malware by taking it to a computer technician as there was no way for technicians to decypt the files - you had to pay the ransom.
It was an instant success as far as criminal business models go, and soon there were many variants of ransomware infecting users around the world. Early editions also accepted the still widely used Ukash and MoneyPak as forms of payment, but would provide a discount for Bitcoin. This set the precedence for a preference of cryptocurrency over preloaded cash cards and from then on out Ransomware
and Cryptocurrency have gone hand in hand.
Glossary Blog Back to the Malware Manifesto