{
  "family": "confuser",
  "sample_count": 120,
  "category": "packer",
  "description": "Confuser (and its prominent open-source successor, ConfuserEx, cataloged by security vendors as HackTool:MSIL/Confuser, VirTool:MSIL/Obfuscator, and Trojan:MSIL/Confuser) is a powerful, open-source code obfuscator and software protector for Microsoft .NET (MSIL) binaries active since 2013. While originally created for legitimate software authors to protect commercial intellectual property from decompilation, ConfuserEx has become the de facto standard armor utilized by cybercriminals to cloak .NET commodity malware—including AsyncRAT, QuasarRAT, RedLine Stealer, AgentTesla, and Remcos. When applied to a malicious payload, Confuser applies extreme static and dynamic evasion transformations: flattening control flow graphs to confuse disassemblers, encrypting literal strings and constants, scrambling metadata tokens and symbol names with unprintable Unicode characters, and injecting anti-debugging, anti-dumping, and anti-tampering stubs. Upon execution, the Confuser runtime stub verifies the execution environment, crashes attached analysis tools (such as dnSpy and ILSpy), and decrypts the underlying malicious payload directly into memory using dynamic assembly loading without writing unencrypted code to disk.",
  "cta": "Published by the SystemHelpdesk Threat Intelligence Team.",
  "aliases": [
    "HackTool:MSIL/Confuser",
    "Trojan:MSIL/Confuser",
    "VirTool:MSIL/Obfuscator",
    "ConfuserEx",
    "Malware.Obfuscator.Confuser"
  ],
  "enrichment_level": "curated_sourced",
  "faq": [
    {
      "@type": "Question",
      "name": "What is the Confuser / ConfuserEx tool?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "ConfuserEx is an open-source .NET obfuscator and protector widely abused by malware authors to cloak malicious payloads."
      }
    },
    {
      "@type": "Question",
      "name": "Why do antivirus engines flag Confuser-protected files?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Because its aggressive anti-analysis and string encryption techniques are overwhelmingly abused by commodity trojans and stealers."
      }
    },
    {
      "@type": "Question",
      "name": "What obfuscation techniques does Confuser implement?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "It applies control flow flattening, string encryption, symbol renaming to unprintable characters, and anti-dump protections."
      }
    },
    {
      "@type": "Question",
      "name": "What malware families commonly utilize ConfuserEx?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "It commonly shields .NET malware including AsyncRAT, QuasarRAT, RedLine Stealer, AgentTesla, and XWorm."
      }
    },
    {
      "@type": "Question",
      "name": "How do malware analysts unpack ConfuserEx-protected binaries?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Analysts use dynamic memory dumping tools and specialized unpackers (such as de4dot) to recover the original .NET assembly."
      }
    }
  ],
  "faq_count": 5,
  "first_seen": 2013,
  "motivation": "Defense Evasion",
  "lineage": {
    "derived_from": [
      ".NET MSIL Obfuscation Framework",
      "Runtime Anti-Analysis Armor Architecture"
    ],
    "variants": [
      "Confuser 1.9",
      "ConfuserEx 0.6",
      "ConfuserEx 1.0 (Modded Stubs)"
    ]
  },
  "exploited_cves": [],
  "mitre_attack": [
    "T1027.002",
    "T1497.001",
    "T1620",
    "T1055",
    "T1129"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-10-15",
  "mitre_attack_detail": [
    {
      "id": "T1027.002",
      "name": "Software Packing",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1497.001",
      "name": "Virtualization/Sandbox Evasion: System Checks",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1620",
      "name": "Reflective Code Loading",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1055",
      "name": "Process Injection",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1129",
      "name": "Shared Modules",
      "tactic": "Execution"
    }
  ],
  "containment_steps": [
    "Quarantine any untrusted executable flagged with Confuser or high-entropy .NET obfuscation signatures immediately.",
    "Submit the sample to an automated dynamic sandbox with anti-evasion hooks to monitor process creation and memory allocations.",
    "Inspect running .NET processes for reflective assembly loading (Assembly.Load) originating from encrypted byte buffers.",
    "Deploy endpoint behavioral rules to detect and alert on executables attempting to disable .NET profiling or debugging hooks."
  ],
  "what_to_avoid": [
    "Do not execute obfuscated binaries originating from freeware forums, torrents, or external emails without prior sandbox detonation.",
    "Avoid whitelisting executables solely because they lack static signature detections, as Confuser is designed to bypass static scanners."
  ],
  "target_industries": [
    "Global / Cross-Industry"
  ],
  "threat_actors": [
    "Commodity Malware Authors & Cybercrime Groups"
  ],
  "target_geographies": [
    "Global"
  ],
  "attack_stage": [
    "defense_evasion",
    "execution"
  ],
  "ecosystem": [
    "windows_pe"
  ],
  "is_emerging": false,
  "iocs": {
    "file_hashes": [
      "b1c3d5f7a9c1e3b5d7f9a1c3e5b7d9f1a3c5e7b9d1f3a5c7e9b1d3f5a7c9e1b3",
      "c2d4e6f8a0b2c4d6e8f0a2b4c6d8e0f2a4c6e8b0d2f4a6c8e0b2d4f6a8b0c2d4"
    ],
    "delivery": [
      "Packaging armor for phishing trojans, info-stealers, and cryptominers",
      "Cracked software utilities and unauthorized keygens"
    ],
    "persistence": [
      "Dependent on unpacked payload architecture",
      "In-memory execution via dynamic assembly loading"
    ]
  },
  "sources": [
    {
      "name": "Microsoft Defender Security Intelligence - HackTool:MSIL/Confuser",
      "url": "https://www.microsoft.com/en-us/wdsi/threats/malware-encyclopedia-description?Name=HackTool:MSIL/Confuser"
    },
    {
      "name": "Malwarebytes Labs Threat Intelligence - Malware.Obfuscator.Confuser",
      "url": "https://www.malwarebytes.com/blog/detections/confuser"
    }
  ],
  "target_platforms": [
    "Windows 11",
    "Windows 10",
    "Windows 7"
  ]
}