{
  "family": "liudoor",
  "sample_count": 1,
  "category": "ransomware",
  "description": "<h3>Executive Summary</h3>\nLiudoor is a malicious Backdoor Trojan designed to covertly infiltrate Windows systems, establish stealthy persistence, and provide a remote attacker with unfettered, unauthorized access to the compromised machine. Unlike simple downloaders, a backdoor allows the threat actor to directly interact with the system, execute arbitrary commands, and manually exfiltrate sensitive data.\n\n<h3>Infection Vector and Technical Capabilities</h3>\nLiudoor is typically distributed through targeted spear-phishing campaigns containing malicious attachments (often macro-enabled Office documents or weaponized PDFs) or by exploiting unpatched vulnerabilities in public-facing web servers or RDP (Remote Desktop Protocol) endpoints.\n\nOnce executed, Liudoor focuses on establishing a secure, persistent connection to the attacker:\n<ul>\n<li><strong>Command and Control (C2) Communication:</strong> The backdoor establishes a connection to a remote C2 server, often over encrypted channels (HTTPS) or via custom protocols on non-standard ports to evade Intrusion Detection Systems (IDS). It actively \"listens\" for incoming commands.</li>\n<li><strong>Remote Code Execution (RCE):</strong> The core functionality of Liudoor is to provide a remote shell. The attacker can execute arbitrary system commands (`cmd.exe` or PowerShell), upload or download files, and manipulate the Windows Registry at will.</li>\n<li><strong>Lateral Movement Facilitation:</strong> Because the attacker has interactive control, Liudoor is frequently used as a \"beachhead.\" The attacker will use the compromised host to scan the internal network, dump local credentials (using tools like Mimikatz), and pivot to more valuable servers or Domain Controllers.</li>\n</ul>\n\n<h3>Threat Assessment</h3>\nA Liudoor infection is a critical security incident. The presence of an active backdoor means the network perimeter has completely failed, and a human adversary currently has interactive access to the internal network. Data exfiltration or the deployment of enterprise-wide ransomware is often imminent.\n\n<h3>Incident Response and Remediation</h3>\n<ul>\n<li><strong>Immediate Isolation:</strong> The highest priority is to physically disconnect the infected machine from the network to sever the attacker's interactive connection and prevent further lateral movement. Do not power off the machine, as volatile memory (RAM) is required for forensic analysis.</li>\n<li><strong>Forensic Triage:</strong> Utilize Endpoint Detection and Response (EDR) or memory forensics to identify the specific processes associated with Liudoor, analyze its network connections to identify the C2 infrastructure, and determine if local administrator credentials have been dumped.</li>\n<li><strong>Enterprise Password Reset and Re-imaging:</strong> Because the attacker had interactive access, all credentials used on or accessible from the compromised endpoint must be reset immediately. The endpoint itself must undergo a complete bare-metal wipe and re-image from a trusted baseline.</li>\n</ul>",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [
    "Backdoor.Liudoor",
    "Trojan.Liudoor",
    "Win32/Liudoor"
  ],
  "enrichment_level": "insufficient_information",
  "faq": [],
  "faq_count": 0,
  "mitre_attack": [
    "T1059.003",
    "T1105",
    "T1573.001",
    "T1021"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-07-02T06:41:13Z",
  "type": "Backdoor / Trojan",
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ]
}