What is CryptoDefense Ransomware?

CryptoDefense is an advanced subset of CryptoLocker Ransomware that appeared around 2014. It used public-key cryptography (PKC), and targeted computers running the Windows operating system (OS). The infection was spread through spam emails with infected PDF documents. Victims were often given 72 hours to pay ransom, collected largely in bitcoin (BTC), in order to regain access to their infected files which would otherwise be permanently deleted.