The earliest CryptoLocker samples appear to have been released on the Internet on September 5, 2013.

CryptoLocker changes this dynamic by aggressively encrypting files on the victim's system and returning control of the files to the victim only after the ransom is paid. Victims of these traditional forms of ransomware could ignore the demands and use security software to unlock the system and remove the offending malware. These consequences, such as owing a fine or facing arrest and prosecution, are presented as being the result of a fabricated indiscretion like pirating music or downloading illegal pornography. Ransomware prevents victims from using their computer normally (e.g., by locking the screen) and uses social engineering to convince victims that failing to follow the malware authors' instructions will lead to real-world consequences. Ransomware malware such as Reveton, Urausy, Tobfy, and Kovter has cost consumers considerable time and money over the past several years.

In mid-September 2013, the SecureWorks® CTU™ security intelligence research team, a thought leader in IT Security services, observed a new ransomware malware family called CryptoLocker.

What is crypto locker