Cyberreason's RansomFree is a ransomware protection program that silently runs in the background looking for ransomware activity on a computer. If activity is detected, such as the encrypting of certain files, it will automatically terminate the program to prevent your data from being encrypted.
RansomFree utilizes canary files, which are folders of files created throughout the computer. These files are then monitored for any changes by an external program. If RansomFree detects that a file has been modified, it will display a prompt asking if you wish to terminate the program that is trying to access these files.