Security researchers observed the Ryuk ransomware using a special hardware feature to wake up powered-down devices in order to encrypt them.
According to Bleeping Computer, a security researcher observed some samples of Ryuk ransomware spawning subprocesses with “8 LAN” as their argument upon execution. Ryuk leveraged this argument to scan the device’s ARP table. It did so in an effort to check if the listed entries of network devices were part of the “10.,” “172.16.” and/or “192.168” private IP address subnets.
If it found that any of the entries appeared on any of those networks, Ryuk used a hardware feature known as “Wake-on-Lan” to wake up a powered-down device by sending it a “magic packet.” The ransomware then attempted to mount the device’s C$ administrative share and encrypt the computer’s drive in the event that the Wake-on-Lan request was successful. Subsequently, this technique helped Ryuk reach into a corporate network from a single compromised device.
A Look at Ryuk’s Recent Threat Activity
The technique described above is just the latest instance in which Ryuk has made headlines. Back in early December, Emsisoft discovered a bug in a decryptor that Ryuk’s operators provided to paying victims. This security issue, in turn, could have prevented victims from successfully recovering large files encrypted by the ransomware.
Just a few days later, Bleeping Computer reported on a memory dump that contained numerous references to Ryuk and the city of New Orleans, indicating that the threat could have been responsible for the New Orleans ransomware attack. The next day, the U.S. Coast Guard disclosed that a Maritime Transportation Security Act (MTSA) regulated facility had suffered a Ryuk ransomware infection.
How to Defend Against Ryuk Ransomware
Security professionals can help defend against a Ryuk ransomware infection by having the latest threat intelligence to stay on top of emerging attack trends and techniques. Organizations should also implement a solid data backup strategy, test this strategy’s recovery capabilities regularly and isolate backup systems to prevent ransomware attackers from encrypting them.