Description

Security researchers at AhnLab observed that threat actors are now exploiting security vulnerabilities in remote desktop programs like Sunlogin and AweSun to deploy the PlugX malware. This modular malware has been extensively used by threat actors in China, with new features continuously added to help perform system control and information theft. In recent attacks, upon the exploitation of the flaws, the PowerShell command is executed to retrieve an executable and a DLL file from a remote server. This executable is cybersecurity company ESET’s legitimate HTTP Server Service that uses a technique called DLL side loading to load the DLL file and ultimately run the PlugX payload in memory. In addition, the operators of PlugX use a wide variety of trusted binaries that are vulnerable to DLL side-loading, including anti-virus executables, which have proven to be effective at infecting victims. Furthermore, researchers also mentioned that, the PlugX backdoor is notable for its ability to initiate arbitrary services, download and run files from an external source, and drop plugins that can gather data and spread using the Remote Desktop Protocol (RDP).