Abstract
Ransomware has become the most dangerous threat today because of its unique and destructive characteristics. Ransomware encrypts the victim's important files and then requires money to decrypt them. Ransomware has become among the most preferred measures for cybercriminals to earn money. Moreover, the technology for producing ransomware continues to evolve; as a result, it has becomes more difficult to defend. In this study, we analyze major ransomware including WannaCry and propose a method to protect valuable files from existing ransomware. To this end, the moving target defense method is applied by randomly changing the file extensions that ransomware attempts to encrypt. We show that our proposed method can successfully protect files from ransomware. Finally, we present the proposed method which can be reasonably used without performance degradation. (C) 2019 Elsevier Ltd. All rights reserved.