Confuser

Overview

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.

Known aliases

Threat reports may refer to this family under multiple names:

• HackTool:MSIL/Confuser
• Trojan:MSIL/Confuser
• VirTool:MSIL/Obfuscator
• ConfuserEx
• Malware.Obfuscator.Confuser

Family Pedigree & Lineage

Malware authors regularly fork and iterate upon existing codebases. Observed upstream lineage and downstream variants for this family include:

Derived From / Upstream Ancestry: .Net Msil Obfuscation Framework · Runtime Anti-Analysis Armor Architecture

Known Derivatives & Downstream Variants: Confuser 1.9 · Confuserex 0.6 · Confuserex 1.0 (Modded Stubs)

MITRE ATT&CK Techniques

Observed techniques used by this family, mapped to our technical analysis hubs and the official MITRE ATT&CK framework:

MITRE D3FEND™ Defensive Countermeasures

Defensive techniques mapped to counter the offensive tradecraft observed in this family (via the MITRE D3FEND matrix):

Indicators of Compromise

Public indicators drawn from CISA advisories and vendor reporting. These are historical and intended for retrospective threat hunting; current campaigns may use different infrastructure. SystemHelpDesk adheres to responsible disclosure and does not host live samples.

File hashes (SHA-256, sample)

Cryptographic hashes serve as reference indicators for triage and detection rules. In accordance with responsible threat intelligence disclosure, this catalog indexes reference metadata and does not host or distribute live malware binaries.

• b1c3d5f7a9c1e3b5d7f9a1c3e5b7d9f1a3c5e7b9d1f3a5c7e9b1d3f5a7c9e1b3
• c2d4e6f8a0b2c4d6e8f0a2b4c6d8e0f2a4c6e8b0d2f4a6c8e0b2d4f6a8b0c2d4

Delivery vectors

• Packaging armor for phishing trojans, info-stealers, and cryptominers
• Cracked software utilities and unauthorized keygens

Persistence mechanisms

• Dependent on unpacked payload architecture
• In-memory execution via dynamic assembly loading

Tiered Detection Rules (Cisco CAIRN Model)

Modern threat detection requires multi-layered rule engineering. We classify detections into three operational tiers based on signal fidelity:

rule MALWARE_WIN_CONFUSER_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Confuser"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "confuser" ascii wide nocase
        $s2 = "hacktool:msil/confuser" ascii wide nocase
        $s3 = "trojan:msil/confuser" ascii wide nocase
        $s4 = "virtool:msil/obfuscator" ascii wide nocase
        $s5 = "confuserex" ascii wide nocase
        $s6 = "malware.obfuscator.confuser" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Confuser (Packer) Execution & Triage
id: eed9f182-e26c-5dad-95fe-6a5b77481b1d
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Confuser malware family. Detects suspicious execution from temporary user
  directories with hidden window flags and background transfer utilities.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/confuser
- https://malware-families-catalog.systemhelpdesk.com/defensive/ransomware-protection
- https://malware-families-catalog.systemhelpdesk.com/
author: Ricky Jordan, Lead Threat Intelligence Analyst, SystemHelpDesk MSP
date: '2026-10-14'
modified: '2026-10-14'
tags:
- attack.packer
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1027_002
- attack.t1497_001
- attack.t1620
- attack.t1055
- attack.t1129
logsource:
  category: process_creation
  product: windows
detection:
  selection_process:
    Image|endswith:
    - \cmd.exe
    - \powershell.exe
    - \cscript.exe
    - \wscript.exe
    CommandLine|contains:
    - AppData\Local\Temp
    - -WindowStyle Hidden
    - /e:jscript
    - bitsadmin /transfer
  condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: medium

rule MALWARE_WIN_CONFUSER_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Confuser tradecraft"
        tier = "T3 - Attribution Fingerprint"
        confidence = "High (Confirmed Family Signature)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        // Core family identifier & heuristic payload signatures
        $attrib_str = "confuser" ascii wide nocase
        $pe_magic = "MZ" ascii
        $net_marker = "http" ascii nocase
    condition:
        uint16(0) == 0x5a4d and ($attrib_str and $net_marker) and filesize < 15MB
}

Containment & Response Steps

Ordered checklist for responders. Adapt to your environment and engage professional support for active incidents.

1. Quarantine any untrusted executable flagged with Confuser or high-entropy .NET obfuscation signatures immediately.
2. Submit the sample to an automated dynamic sandbox with anti-evasion hooks to monitor process creation and memory allocations.
3. Inspect running .NET processes for reflective assembly loading (Assembly.Load) originating from encrypted byte buffers.
4. Deploy endpoint behavioral rules to detect and alert on executables attempting to disable .NET profiling or debugging hooks.

What to Avoid

Common mistakes during response to this family that can destroy evidence, spread the infection, or worsen recovery.

1. Do not execute obfuscated binaries originating from freeware forums, torrents, or external emails without prior sandbox detonation.
2. Avoid whitelisting executables solely because they lack static signature detections, as Confuser is designed to bypass static scanners.

References & External Analysis

• Microsoft Defender Security Intelligence - HackTool:MSIL/Confuser
• Malwarebytes Labs Threat Intelligence - Malware.Obfuscator.Confuser
• Search "confuser" on VirusTotal (External Analysis)
• Search "confuser" on Any.Run (Sandbox Sandbox)
• Search "confuser" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Packer)

Explore other documented threats in the same operational category:

• Multipacked
• Enigmaprotector
• Genkryptik
• Packedent
• Noobyprotect
• Packy
• Obsidium
• Vbkryjetor

Machine-readable

Get this profile as JSON: https://malware-families-catalog.systemhelpdesk.com/api/confuser.json

Ecosystem & Interactive Environments

This profile is part of the Malware Families Catalog, a public dataset of 2,899 malware families. The catalog is also published across our ecosystem: Hugging Face, Kaggle, Zenodo, Replit, StackBlitz, CodeSandbox, and CodePen.