Trojan:Win64/OyesterLoader!rfn

From a technical perspective, Trojan:Win64/OyesterLoader!rfn serves as a first-stage delivery mechanism. Its design incorporates stealth and persistence to ensure delivery of secondary payloads, and its activity is consistent with advanced loader operations. Infection chains begin with a method of initial access, through users launching of a malicious file that masquerades as benign software.  

When the file is launched, the loader establishes persistence by writing files to what are considered low-security locations, like the user's %TEMP% or %APPDATA% directories and often uses file names like legitimate Windows processes to escape civilian scrutiny. An essential capability is establishing command-and-control (C2) communications. The trojan has obfuscated or encrypted strings that resolve to the IP addresses or domain names for the operators' legitimate servers. The resulting beaconing and request for secondary payloads go undetected in otherwise benign network traffic. 

To ensure survivability, the trojan commonly creates persistence mechanisms, such as scheduled tasks or registry run keys, which allow it to re-initiate its sequence after a system reboot. The final and most critical action is the successful download and launch of a secondary payload, which constitutes the primary threat, such as a ransomware binary or a data exfiltration tool. The "Win64" designation confirms it targets the 64-bit Windows operating systems that form the backbone of most corporate environments.