Dofoil

Overview

Dofoil (universally tracked across threat intelligence communities and security vendors under aliases including SmokeLoader, Smoke Loader, and Trojan:Win32/Dofoil) is a notorious, modular initial access malware loader active since at least 2011. Sold on Russian-language underground cybercrime forums as a commercial Malware-as-a-Service (MaaS) payload loader, Dofoil served as the primary gateway infection for distributing ransomware, banking trojans, cryptocurrency miners, and info-stealers across global enterprise and consumer endpoints. Dofoil was a primary target of the major 2024 international law enforcement takedown known as 'Operation Endgame'. To maintain stealth, Dofoil injects its payload stub directly into legitimate Windows processes (most commonly explorer.exe) and manually reloads a fresh copy of ntdll.dll from disk directly into memory to overwrite and bypass user-mode API monitoring hooks established by Endpoint Detection and Response (EDR) solutions. In addition, Dofoil generates decoy HTTP requests to benign domains (such as microsoft.com and google.com) interspersed with encrypted command-and-control beacons to camouflage its network footprint.

Known aliases

Threat reports may refer to this family under multiple names:

• Trojan:Win32/Dofoil
• SmokeLoader
• Smoke Loader
• TrojanDownloader:Win32/Dofoil

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: Underground Russian Maas Loaders

Known Derivatives & Downstream Variants: Smokeloader 2014 · Smokeloader 2018 · Smokeloader 2024

MITRE ATT&CK Techniques

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

Tactical Mitigations

Based on the techniques used by this family, consider the following defensive strategies:

• T1105: Implement network intrusion detection systems (NIDS) and host-based firewalls to block unauthorized inbound or outbound file transfers.

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.

• d4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a1b2c3d4e5
• a1b2c3d4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a1b2

Delivery vectors

• invoice_scan.docm
• smoke_loader.exe

Persistence mechanisms

• HKCU\Software\Microsoft\Windows\CurrentVersion\Run\DofoilLoader
• %AppData%\Dofoil\explorer_svc.exe

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_DOFOIL_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Dofoil"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "dofoil" ascii wide nocase
        $s2 = "trojan:win32/dofoil" ascii wide nocase
        $s3 = "smokeloader" ascii wide nocase
        $s4 = "smoke loader" ascii wide nocase
        $s5 = "trojandownloader:win32/dofoil" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Dofoil (Downloader) Execution & Triage
id: 7a765b5f-d523-556d-bb11-c29375f104cf
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Dofoil 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/dofoil
- 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.downloader
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1566_001
- attack.t1055_001
- attack.t1059_003
- attack.t1547_001
- attack.t1105
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_DOFOIL_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Dofoil 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 = "dofoil" 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. Isolate the endpoint immediately; a Dofoil/Smoke Loader infection almost guarantees the presence of severe secondary payloads like ransomware.
2. Do NOT reboot the machine. Capture a full forensic memory image (RAM dump) immediately to preserve the injected, memory-resident payloads.
3. Audit the Windows Task Scheduler and Registry Run keys to identify and remove the Dofoil persistence mechanisms.
4. Assume total endpoint compromise; perform a clean OS rebuild and force password resets for all accounts that accessed the machine.

What to Avoid

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

1. Do not close an incident simply because the initial Dofoil dropper was quarantined; the payload often executes purely in memory.
2. Avoid relying solely on manual file deletion, as the injected processes will likely just recreate the dropped binaries.

References & External Analysis

• Huntress Threat Research - Deconstructing SmokeLoader / Dofoil
• Zscaler ThreatLabz - SmokeLoader Analysis & Operation Endgame
• Search "dofoil" on VirusTotal (External Analysis)
• Search "dofoil" on Any.Run (Sandbox Sandbox)
• Search "dofoil" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Downloader)

Explore other documented threats in the same operational category:

• Tempedreve
• Upatre
• Amonetize
• Nymaim
• Gepys
• Banload
• Nymeria
• Rubinurd

Machine-readable

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