A campaign that has been active for the past few months has been leveraging compromised websites to spread fake software updates that in some cases delivered the NetSupport Manager remote access tool (RAT), FireEye reports.
A commercially available RAT, NetSupport Manager is employed by administrators for remote access to client computers. However, the legitimate application can also be abused by malicious actors who install it on victim computers without the owners’ knowledge, to gain unauthorized access to their machines.
This function collects various system information, encodes it and sends it to the server: architecture, computer name, user name, processors, OS, domain, manufacturer, model, BIOS version, anti-spyware product, anti-virus product, MAC address, keyboard, pointing device, display controller configuration, and process list.
The server then responds with encoded content: a function named step3 and Update.js, which downloads and executes the final payload.
The code leverages PowerShell commands to download multiple files from the server, including a 7zip standalone executable, a password-protected archive file containing the RAT, and a batch script to install the NetSupport client on the system.
The batch script was also designed to disable Windows Error Reporting and App Compatibility, add the remote control client executable to the firewall’s allowed program list, add a Run registry entry or download a shortcut file to Startup folder for persistence, hide files, delete artefacts, and execute the RAT. During analysis, the researchers noticed that the script was regularly updated by the malware.
With the help of NetSupport Manager, attackers could gain remote access to the compromised systems, transfer files, launch applications, get the system’s location, and remotely retrieve inventory and system information.