The Ryuk Ransomware uses the Wake-on-Lan feature to turn on powered off devices on a compromised network to have greater success encrypting them. The feature allows a powered down device to be woken up, or powered on, by sending a special network packet to it. This is useful for administrators who may need to push out updates to a computer or perform scheduled tasks when it is powered down. Ryuk will then attempt to mount the remote device’s C$ administrative share.
Source: https://www.bleepingcomputer.com/news/security/ryuk-ransomware-uses-wake-on-lan-to-encrypt-offline-devices/