Donloz
Overview
Executive Summary
Donloz is a malicious downloader Trojan engineered to stealthily infiltrate a target system, establish a hidden foothold, and subsequently download and execute secondary malware payloads. It acts as a critical intermediary in complex infection chains, often preceding the deployment of highly destructive threats like ransomware or banking trojans.Infection Vector and Execution Flow
Donloz is typically distributed via highly targeted spear-phishing campaigns. The emails utilize socially engineered lures (e.g., fake invoices, shipping notices) containing malicious macro-enabled Microsoft Office documents or ZIP archives containing heavily obfuscated scripts (VBScript or JavaScript). Upon execution of the initial lure, Donloz is deployed onto the system. Its primary operational phases include:- Reconnaissance and Evasion: Donloz immediately checks its environment to ensure it is not running within a malware analysis sandbox or virtual machine. It may also check the system locale to avoid infecting targets in specific geographic regions.
- C2 Communication: The Trojan reaches out to a hardcoded or dynamically generated command-and-control (C2) server. It transmits a basic fingerprint of the infected machine (OS version, installed antivirus) to the attacker.
- Payload Delivery: Based on the transmitted fingerprint, the C2 server instructs Donloz to download a specific secondary payload. This payload is often injected directly into the memory of a legitimate process (like `explorer.exe`) to evade file-based detection.
Security Implications
A Donloz infection indicates a severe perimeter breach. While the Donloz executable itself may not directly steal data, its successful execution guarantees that a secondary, potentially catastrophic payload is either imminent or already active on the network.Eradication and Incident Response
- Advanced EDR Detection: Configure EDR platforms to monitor for anomalous parent-child process relationships, specifically office applications (`winword.exe`, `excel.exe`) spawning command shells (`cmd.exe`) or PowerShell, which is indicative of a Donloz downloader script executing.
- Network Isolation: Immediately isolate the affected endpoint to interrupt the Donloz C2 communication and prevent the download of the secondary payload.
- Comprehensive Sweeps: A standard antivirus scan is insufficient. Perform a deep forensic sweep to locate the Donloz persistence mechanisms (registry keys) and identify/remove the specific secondary payload it downloaded.
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: T1105 T1059 T1055.001
Tactical Mitigations
Based on the techniques used by this family, consider the following defensive strategies:
- T1059: Restrict execution of scripting languages such as PowerShell, VBScript, or Python to authorized administrators. Enforce Script Block Logging.
- T1105: Implement network intrusion detection systems (NIDS) and host-based firewalls to block unauthorized inbound or outbound file transfers.
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_DONLOZ {
meta:
description = "Detects Donloz (ransomware)"
author = "SystemHelpdesk Boilerplate Generator"
date = "2026-07-06"
strings:
$s1 = "donloz" ascii wide nocase
$s2 = "downloader.donloz" ascii wide nocase
$s3 = "trojan.donloz" ascii wide nocase
$s4 = "win32/donloz" ascii wide nocase
condition:
uint16(0) == 0x5a4d and any of them
}Sigma Rule
title: Suspicious Donloz Activity
id: 4c6e02dababcd71daa707af20b6958b0
status: experimental
description: Detects generic indicators of the donloz malware family.
logsource:
category: process_creation
product: windows
detection:
selection:
Image|endswith:
- '\cmd.exe'
- '\powershell.exe'
CommandLine|contains:
- "*donloz*"
- "*downloader.donloz*"
- "*trojan.donloz*"
- "*win32/donloz*"
condition: selection
level: mediumReferences & External Analysis
- Search "donloz" on VirusTotal (External Analysis)
Frequently Asked Questions
How do I remove the Donloz Ransomware from Windows?
Manual removal of Donloz 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 Donloz a virus or a Ransomware?
Donloz is classified as a Ransomware. Unlike traditional viruses that infect files, modern malware like Donloz typically operates as a standalone payload designed to compromise systems, steal data, or deploy secondary stage implants.
What are the main symptoms of a Donloz infection?
Symptoms of Donloz 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 Donloz 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/donloz.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.