Threat actors are exploiting an open-source rootkit named Reptile to specifically target Linux systems in South Korea, as detailed in a report by AhnLab Security Emergency Response Center (ASEC).
What sets Reptile apart from other rootkit malware is its inclusion of a reverse shell, giving attackers the ability to gain control over compromised systems. This advanced rootkit employs port knocking techniques, creating a standby state on infected systems that can be activated by a magic packet sent by threat actors to establish a connection with a command and control server.
Rootkits are malicious software designed to provide unauthorized privileged access to a machine while evading detection. At least four distinct campaigns have utilized Reptile since 2022. Trend Micro first identified Reptile’s use in May 2022, linking it to the Earth Berberoka intrusion set, which concealed connections and processes associated with a cross-platform Python trojan called Pupy RAT in attacks on gambling sites in China. Additional instances of Reptile deployment include attacks facilitated by UNC3886, a China-linked threat actor, and a cryptojacking operation uncovered by Microsoft.
A deeper examination of Reptile reveals its loader mechanism, utilizing a tool called kmatryoshka to decrypt and load the rootkit’s kernel module into memory. Subsequently, it creates a specific port that awaits a magic packet from threat actors, leading to the establishment of a connection with a command-and-control server.
Despite its concealment capabilities for files, directories, processes, and network communications, Reptile’s reverse shell functionality makes systems vulnerable to being hijacked by threat actors. To defend against such attacks, organizations are encouraged to bolster their cybersecurity measures, including software updates and careful software sourcing.