{
  "family": "msilbot",
  "sample_count": 1,
  "category": "ransomware",
  "description": "<h3>Executive Summary</h3>\nMSILBot (often detected as MSIL.Trojan or MSIL.Bot) refers to a broad category of botnet malware and remote access trojans (RATs) that are written and compiled using the Microsoft .NET framework (MSIL - Microsoft Intermediate Language). Because the .NET framework is deeply integrated into modern Windows operating systems, MSIL-based malware is highly prevalent, easy for attackers to develop rapidly, and capable of executing complex tasks without requiring additional runtime libraries.\n\n<h3>Infection Vector and Technical Capabilities</h3>\nMSILBots are distributed through various vectors, including malspam campaigns containing macro-enabled documents, malicious links in Discord or Telegram, and bundled with pirated software. They are often protected by readily available .NET obfuscators (like ConfuserEx) to evade static signature detection.\n\nUpon execution, MSIL-based bots exhibit versatile capabilities:\n<ul>\n<li><strong>Just-In-Time (JIT) Compilation:</strong> The MSIL code is compiled into native machine code on the fly by the .NET runtime when executed, which can sometimes bypass simplistic behavioral analysis engines that struggle to monitor JIT processes.</li>\n<li><strong>Comprehensive Botnet Functionality:</strong> Once active, the bot connects to a C2 server (often via HTTP or IRC) and awaits commands. Typical capabilities include downloading secondary payloads, executing arbitrary shell commands, launching DDoS attacks (UDP/TCP flooding), and acting as a proxy.</li>\n<li><strong>Information Stealing:</strong> Many MSIL bots incorporate modules to scrape memory, log keystrokes, and extract saved credentials from web browsers and email clients.</li>\n</ul>\n\n<h3>Threat Assessment</h3>\nAn MSILBot infection is a severe security incident. It indicates that the infected endpoint has been compromised and incorporated into a larger botnet, granting remote attackers full administrative control over the machine. The versatility of .NET means the bot can quickly be repurposed from a simple DDoS node to a devastating info-stealer or ransomware loader.\n\n<h3>Incident Response and Remediation</h3>\n<ul>\n<li><strong>Immediate Network Isolation:</strong> The highest priority is to disconnect the endpoint from the network to sever communication with the botnet C2 infrastructure and halt any active data exfiltration or DDoS participation.</li>\n<li><strong>Behavioral Analysis (EDR):</strong> EDR solutions must be tuned to monitor the .NET runtime (`mscoree.dll`, `clr.dll`) for anomalous behavior, such as a supposedly benign application spawning `cmd.exe` or initiating high-volume outbound network connections.</li>\n<li><strong>Complete Re-imaging:</strong> Due to the potential for the bot to have downloaded multiple secondary payloads and established deep persistence, attempting to manually \"clean\" the system is highly risky. A complete bare-metal wipe and re-image from a trusted baseline is necessary.</li>\n</ul>",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [
    "Trojan.MSIL",
    "MSIL.Bot",
    "Win32/MSIL.Agent"
  ],
  "enrichment_level": "insufficient_information",
  "faq": [],
  "faq_count": 0,
  "mitre_attack": [
    "T1059",
    "T1105",
    "T1071.001"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-07-02T07:12:52Z",
  "type": "Botnet / Trojan (.NET)",
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ]
}