{
  "family": "radmin",
  "sample_count": 2,
  "category": "ransomware",
  "description": "RemoteAdmin:Win32/Radmin (Remote Administrator) is a legitimate, commercial remote control software application. However, because it provides full, interactive GUI access, file transfer capabilities, and operates silently in the background (as a Windows Service), it is frequently weaponized by advanced threat actors (APTs) and ransomware cartels. They deploy it as a stealthy, persistent backdoor to maintain access and facilitate lateral movement across a compromised network (`T1219`).<br><br><b>Understanding Radmin (Abused Legitimate Tools)</b><br>To an end-user, Radmin operates invisibly if configured as a service by an attacker. For a security team, the unauthorized presence of Radmin is a 'Code Red'. Like AnyDesk or TeamViewer, it is a classic 'Living off the Land' tool. Because the binaries (`rserver3.exe`, `FamImaf.sys`) are digitally signed by a legitimate software company (Famatech), many antivirus engines will ignore them by default, allowing the attacker unfettered access.<br><br><b>Execution and Abuse Mechanics</b><br>Attackers do not typically use Radmin for initial access. It is deployed post-compromise (`T1105`). Once an attacker has administrative rights on a machine (e.g., via compromised credentials), they silently install the Radmin Server component (`T1543.003`). They configure it to hide its system tray icon, set a strong custom password, and open a listening port (default is TCP 4899). The attacker can now connect to this machine from anywhere, completely bypassing standard EDR behavioral checks, as the remote activity appears to be legitimate administrative work.<br><br><b>Indicators of Compromise & Impact</b><br>The impact is total, interactive control of the host and a launchpad for lateral movement. Host-based IoCs include the presence of `rserver3.exe`, the associated Famatech driver files, and the creation of the 'Radmin Server' Windows service. EDR should monitor for the installation of these binaries in unusual directories (e.g., `%Temp%`). Network IoCs include inbound connections on TCP port 4899 (or a custom configured port) originating from outside the recognized corporate admin subnets.",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [],
  "faq_count": 0,
  "mitre_attack": [
    "T1105",
    "T1219",
    "T1543.003"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-06-09",
  "mitre_attack_detail": [
    {
      "id": "T1219",
      "name": "Remote Access Software (Abusing a commercial RAT for backdoor access)",
      "tactic": "Command and Control"
    },
    {
      "id": "T1543.003",
      "name": "Create or Modify System Process: Windows Service (Installing Radmin Server for persistence)",
      "tactic": "Persistence"
    },
    {
      "id": "T1105",
      "name": "Ingress Tool Transfer (Deploying the Radmin binaries post-compromise)",
      "tactic": "Command and Control"
    }
  ],
  "containment_steps": [
    "Immediately terminate the `rserver3.exe` process and isolate the machine to sever the attacker's interactive connection.",
    "Assume the attacker has compromised all credentials on the machine and potentially mapped the internal network; initiate a broad incident response.",
    "Use EDR to hunt for the presence of `rserver3.exe` and its associated registry keys (`HKLM\\SOFTWARE\\Radmin`) across the entire enterprise to find lateral movement.",
    "Block TCP port 4899 (and investigate any custom ports discovered in the registry config) at the internal network boundaries."
  ],
  "what_to_avoid": [
    "Do not assume Radmin is a false positive just because it is a legitimate tool; if your IT department doesn't use it, it is a severe threat.",
    "Avoid simply uninstalling the software; you must investigate what the attacker did while they had interactive access (e.g., deployed ransomware, dumped credentials)."
  ],
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ]
}