Ryuk is the name of a ransomware family, first discovered in the wild in August 2018. It is one of the nastiest ransomware going around. Ryuk will lock your files or systems and holds them hostage for ransom. Ryuk is a type of ransomware used in targeted attacks, where the threat actors make sure that essential files are encrypted so they can ask for large ransom amounts. A typical Ryuk ransom demand can amount to a few hundred thousand dollars. Ryuk is one of the first ransomware families to include the ability to identify and encrypt network drives and resources, as well as delete shadow copies on the endpoint. This means the attackers can then disable Windows System Restore for users, making it impossible to recover from an attack without external backups.
Ryuk is delivery method is spam emails. These emails are often sent from a spoofed address, so the sender name does not raise suspicion.