Ransomware
Cryptowall
CryptoWall is a ransomware, is usually spread by spam and phishing emails, malicious ads, hacked websites, or other malware and uses a Trojan horse to deliver the malicious payload.
Cryptowall is a Windows ransomware.
Background
CryptoWall is a ransomware typically propagated through spam and phishing emails, malicious advertisements, compromised websites, or other malware, relying on a Trojan horse to deliver its malicious payload.
Source: Malpedia (Fraunhofer FKIE).