CryptoLocker is a type of ransomware that emerged in 2013 and whose objective is to infect victims using PCs with Microsoft Windows installed. As is the case with most ransomware, the main distribution method is spam emails with malicious attachments. CryptoLocker relies on external infrastructure (a botnet) to launch its attacks and, when activated, encrypts the files and data stored on the local device, but also those in cloud storage accounts, if, for example, the Dropbox account is synced locally on the affected PC. CryptoLocker then displays a message so the victims can know that paying a ransom in bitcoins is necessary if they want to get the decryption key (which is stored on the servers controlled by the cybercriminals).