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. Wake-on-Lan is a hardware feature that 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.
Source: Bleeping Computer
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