{
  "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": [
    {
      "@type": "Question",
      "name": "What is Radmin and what threat category does it belong to?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Radmin is classified as a Ransomware. Documented across security telemetry, it is engineered to execute unauthorized operations, establish persistent footholds on target endpoints, and facilitate malicious campaigns targeting enterprise and individual environments."
      }
    },
    {
      "@type": "Question",
      "name": "How does Radmin establish persistence and evade defensive controls?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Radmin typically establishes persistence through registry run keys, scheduled tasks, or service installations, while evading signature-based antivirus solutions through code obfuscation, memory injection, or anti-analysis sandbox checks."
      }
    },
    {
      "@type": "Question",
      "name": "What are the essential incident response steps for mitigating a Radmin compromise?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Security teams responding to Radmin should immediately isolate affected endpoints from the network, perform memory triage to capture volatile forensic artifacts, audit registry and startup persistence mechanisms, revoke exposed user credentials, and restore systems from verified, clean backups."
      }
    },
    {
      "@type": "Question",
      "name": "What cryptographic algorithms and file targeting techniques does Radmin employ during execution?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Radmin typically leverages hybrid cryptographic architectures combining symmetric stream or block ciphers (such as AES-256 or ChaCha20) for rapid file encryption with asymmetric algorithms (such as RSA-2048 or Curve25519) to securely protect the session keys. It aggressively targets sensitive file extensions including corporate documents, databases, virtual disks, and backups while systematically executing commands to delete Volume Shadow Copies (vssadmin delete shadows /all /quiet) and disable system recovery options."
      }
    },
    {
      "@type": "Question",
      "name": "Are decryptors available for Radmin, and what is the recommended recovery procedure?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Decryption availability for Radmin depends on whether security researchers or law enforcement (such as the No More Ransom initiative) have recovered the master private keys or discovered flaws in its key generation routines. Victims should never pay the extortion demand, as payment fuels criminal operations without guaranteeing file restoration. The recommended recovery procedure entails isolating infected hosts, conducting forensic disk imaging, identifying the root access vector, and restoring validated systems from immutable offline backups."
      }
    }
  ],
  "faq_count": 5,
  "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": [
    "Healthcare",
    "Critical Infrastructure",
    "Enterprise"
  ],
  "motivation": "Financial Extortion",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ],
  "attack_stage": [
    "defense_evasion",
    "impact"
  ],
  "ecosystem": [
    "windows_pe"
  ],
  "is_emerging": false,
  "target_platforms": [
    "Windows 11",
    "Windows 10",
    "Windows Server 2022",
    "Windows Server 2019"
  ]
}