On September 2013 to late 2014, Cryptolocker was a ransomware attack that had lead to many files being taken hostage with demands of being paid or they would not give the files back.
Cryptolocker was spread through emails and specifically targetted Microsoft Windows users. After it got into your computer, it would begin taking files and would lock them behind a private key. Because of this, you could not access those files which gave you only the option to pay them, either with bitcoin or another cash voucher.
This virus ended up making around or more than $30 million dollars from those who gave in to paying them to get their files back. It is unknown whether they are honest and always give the files back.
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