Threat actors are using an open-source rootkit called
Reptile to target Linux systems in South Korea.
"Unlike other rootkit malware that typically only provide concealment capabilities, Reptile goes a step further by offering a reverse shell, allowing threat actors to easily take control of systems," the AhnLab Security Emergency Response Center (ASEC)
said in a report published this week.
"Port knocking is a method where the malware opens a specific port on an infected system and goes on standby. When the threat actor sends a magic packet to the system, the received packet is used as a basis to establish a connection with the C&C server."