Imaut
Overview
Executive Summary
Imaut (often referred to as Worm.Imaut or AutoRun.Imaut) is a prolific family of legacy worms that primarily spread via removable media, most notably USB flash drives. While considered a "classic" threat, Imaut remains highly prevalent in industrial control systems (ICS), operational technology (OT) environments, and air-gapped networks where USB drives are frequently used to transfer data.Propagation and Execution Lifecycle
Imaut's primary objective is rapid, silent propagation across local networks and physical media. Its execution lifecycle relies heavily on abusing legacy Windows features:- USB AutoRun Exploitation: When an infected USB drive is inserted into a Windows machine, the worm relies on the `AutoRun.inf` feature (or exploits vulnerabilities in how Windows handles shortcut `.lnk` files) to automatically execute its payload without any user interaction.
- System Modification and Hiding: Once active on the host, Imaut copies itself to the Windows System directory and modifies the Registry to ensure it starts upon reboot. Crucially, it alters Windows Explorer settings to hide file extensions and hidden system files, ensuring the user cannot see the malicious executables on the USB drive.
- Continuous Infection Cycle: The worm continuously monitors the system for new removable drives. When a clean USB drive is inserted, Imaut immediately copies itself to the drive, creates a malicious `AutoRun.inf` file, and waits for the drive to be plugged into a new victim machine.
Threat Assessment
While Imaut rarely contains highly destructive payloads (like ransomware), its presence is a massive operational disruption. It can rapidly saturate networks, corrupt files on USB drives, and serve as a "dropper" for more severe malware. Furthermore, its ability to easily bridge "air-gapped" networks makes it a significant threat in critical infrastructure environments.Eradication and Incident Response
- Disable AutoRun/AutoPlay: The most critical defense against Imaut is enforcing strict Group Policy Objects (GPOs) that entirely disable AutoRun and AutoPlay functionality across all drives in the enterprise.
- USB Device Control: Implement endpoint security policies that restrict or completely block the use of unauthorized USB storage devices.
- Registry Remediation: Removing the executable is insufficient. Incident response must include repairing the registry keys altered by the worm to restore the visibility of hidden files and folders, allowing users to verify their drives are clean.
Known aliases
Threat reports may refer to this family under multiple names:
MITRE ATT&CK Techniques
This family has been observed using the following ATT&CK techniques: T1091 T1547.001 T1564.001
Generated Detections (Boilerplate)
These YARA and Sigma rules are auto-generated based on the family name and aliases. They must be heavily tuned before deployment in a production environment.
YARA Rule
rule MALWARE_WIN_IMAUT {
meta:
description = "Detects Imaut (ransomware)"
author = "SystemHelpdesk Boilerplate Generator"
date = "2026-07-06"
strings:
$s1 = "imaut" ascii wide nocase
$s2 = "worm.imaut" ascii wide nocase
$s3 = "w32/imaut" ascii wide nocase
$s4 = "autorun.imaut" ascii wide nocase
condition:
uint16(0) == 0x5a4d and any of them
}Sigma Rule
title: Suspicious Imaut Activity
id: a1b0e25a80ed92224028b0835b7b5e68
status: experimental
description: Detects generic indicators of the imaut malware family.
logsource:
category: process_creation
product: windows
detection:
selection:
Image|endswith:
- '\cmd.exe'
- '\powershell.exe'
CommandLine|contains:
- "*imaut*"
- "*worm.imaut*"
- "*w32/imaut*"
- "*autorun.imaut*"
condition: selection
level: mediumReferences & External Analysis
- Search "imaut" on VirusTotal (External Analysis)
Frequently Asked Questions
How do I remove the Imaut Ransomware from Windows?
Manual removal of Imaut is highly discouraged as it may leave persistence mechanisms intact. We recommend disconnecting the device from the internet and utilizing a professional incident response service or enterprise-grade EDR software to conduct a full forensic sweep.
Is Imaut a virus or a Ransomware?
Imaut is classified as a Ransomware. Unlike traditional viruses that infect files, modern malware like Imaut typically operates as a standalone payload designed to compromise systems, steal data, or deploy secondary stage implants.
What are the main symptoms of a Imaut infection?
Symptoms of Imaut can include unexpected system slowness, unauthorized outbound network traffic to unknown IP addresses, disabled security software, and suspicious background processes running from AppData or Temp directories.
Related Families (Category: ransomware)
Explore other malware families in the same category:
Protect Your Network Against Ransomwares
Want to prevent Imaut and similar threats from compromising your organization? Read our comprehensive defensive guide: Ransomware Protection Guide.
Machine-readable
Get this profile as JSON: https://jordan123234-malware-families-explorer.static.hf.space/api/imaut.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.