Ursnifdropper
Overview
Executive Summary
UrsnifDropper is a specialized, first-stage Trojan designed explicitly to facilitate the delivery and execution of the notorious Ursnif (also known as Gozi) banking trojan. This dropper acts as the initial beachhead in an attack chain, typically evading initial detection mechanisms before pulling down the more destructive secondary payload.Infection Vector and Execution Chain
UrsnifDropper is predominantly distributed via highly coordinated malspam campaigns. These campaigns utilize socially engineered lures—often disguised as invoices, shipping documents, or legal notices—containing malicious macros within Microsoft Office documents (Word or Excel). Upon a user inadvertently enabling macros, the embedded VBA code executes, initiating the dropper's payload. UrsnifDropper immediately employs defense evasion techniques, such as API hashing and checking for virtualized environments (sandbox evasion), to ensure it is running on a genuine victim machine. Once validated, it reaches out to hardcoded, often compromised, command-and-control (C2) servers via HTTP/HTTPS to download the main Ursnif binary. The downloaded payload is then injected directly into the memory of legitimate Windows processes (like `explorer.exe` or `svchost.exe`) via process hollowing or DLL injection, effectively bypassing traditional file-based antivirus scanning.Threat Impact
The successful execution of UrsnifDropper almost invariably leads to a full-blown Ursnif infection. Ursnif is a sophisticated banking trojan capable of web injection, keylogging, and extensive credential theft, leading to severe financial fraud and network compromise.Mitigation Strategies
- Macro Disablement: Enforce strict Group Policy Objects (GPOs) to disable macros downloaded from the internet (Mark of the Web) across all Microsoft Office applications.
- Email Security: Deploy advanced email filtering and sandboxing solutions to detonate and analyze attachments prior to delivery to the end-user inbox.
- Endpoint Detection and Response (EDR): Utilize EDR tools configured to alert on anomalous process injection (e.g., Office applications spawning `powershell.exe` or `cmd.exe`).
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: T1566.001 T1105 T1055.001
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.
- T1566.001: Scan email attachments for malicious macros, scripts, or suspicious archive files.
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_URSNIFDROPPER {
meta:
description = "Detects Ursnifdropper (trojan)"
author = "SystemHelpdesk Boilerplate Generator"
date = "2026-07-06"
strings:
$s1 = "ursnifdropper" ascii wide nocase
$s2 = "trojandropper.ursnif" ascii wide nocase
$s3 = "downloader.ursnif" ascii wide nocase
$s4 = "win32/ursnifdropper" ascii wide nocase
condition:
uint16(0) == 0x5a4d and any of them
}Sigma Rule
title: Suspicious Ursnifdropper Activity
id: e480b5e7a18427a35ef6ebe372f0996b
status: experimental
description: Detects generic indicators of the ursnifdropper malware family.
logsource:
category: process_creation
product: windows
detection:
selection:
Image|endswith:
- '\cmd.exe'
- '\powershell.exe'
CommandLine|contains:
- "*ursnifdropper*"
- "*trojandropper.ursnif*"
- "*downloader.ursnif*"
- "*win32/ursnifdropper*"
condition: selection
level: mediumReferences & External Analysis
- Search "ursnifdropper" on VirusTotal (External Analysis)
Frequently Asked Questions
How do I remove the Ursnifdropper Trojan from Windows?
Manual removal of Ursnifdropper 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 Ursnifdropper a virus or a Trojan?
Ursnifdropper is classified as a Trojan. Unlike traditional viruses that infect files, modern malware like Ursnifdropper typically operates as a standalone payload designed to compromise systems, steal data, or deploy secondary stage implants.
What are the main symptoms of a Ursnifdropper infection?
Symptoms of Ursnifdropper 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: trojan)
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Protect Your Network Against Trojans
Want to prevent Ursnifdropper and similar threats from compromising your organization? Read our comprehensive defensive guide: Banking Trojan Protection.
Machine-readable
Get this profile as JSON: https://jordanricky1604-ship-it.github.io/malware-families-catalog/api/ursnifdropper.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.