CryptoLocker was a ransomware that infected systems around 2013, encrypting users' files and demanding ransom payments in Bitcoin to decrypt the files. It targeted computers worldwide, encrypting files and requiring victims to pay ransom, typically around $300 worth of Bitcoin, to receive decryption keys. An international operation took down CryptoLocker's distribution network in June 2014, but similar ransomware variants using the CryptoLocker name have emerged since.