Ursnifdropper
Table of Contents
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
Observed techniques used by this family, mapped to our technical analysis hubs and the official MITRE ATT&CK framework:
| Technique | Name | Tactic | Official Spec |
|---|---|---|---|
T1566.001 | Phishing: Spearphishing Attachment | Initial Access | ATT&CK ↗ |
T1105 | Ingress Tool Transfer | Command and Control | ATT&CK ↗ |
T1055.001 | Dynamic-link Library Injection | defense-evasion | ATT&CK ↗ |
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.
MITRE D3FEND™ Defensive Countermeasures
Defensive techniques mapped to counter the offensive tradecraft observed in this family (via the MITRE D3FEND matrix):
| D3FEND ID | Countermeasure Name | Tactic | Countered ATT&CK | Defensive Guidance |
|---|---|---|---|---|
D3-DIA | DLL Injection Analysis | Detect | T1055.001 | Monitor remote thread creation (CreateRemoteThread) and unauthorized DLL loading into core Windows processes (svchost.exe, explorer.exe). |
D3-NTI | Network Traffic Inspection | Detect | T1105 | Inspect deep packet payloads for anomalous staging binaries and unauthorized egress protocols. |
D3-FS | File Sandboxing (Attachment Detonation) | Isolate | T1566.001 | Detonate macro-enabled documents, ISOs, and password-protected archives inside an isolated hypervisor. |
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:
Tier 1 Primitive Artifact Rule (Fast Triage)
Matches raw strings and file markers. Vulnerable to binary repacking and simple obfuscation.
rule MALWARE_WIN_URSNIFDROPPER_T1_ARTIFACT {
meta:
description = "Tier 1 Primitive Artifact: Raw string matches for Ursnifdropper"
tier = "T1 - Primitive Artifact"
confidence = "Low-Medium (Fast Triage)"
author = "SystemHelpdesk Threat Research Desk"
date = "2026-10-14"
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
}Tier 2 Behavioral Context Rule (Process Chains & Sigma)
Tracks parent-child process anomalies and suspicious scripting telemetry. Resilient against file renames.
title: SystemHelpDesk Detection - Ursnifdropper (Trojan) Execution & Triage
id: 35d25bc3-d61d-51bd-ad19-09846eb041f7
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
with the Ursnifdropper 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/ursnifdropper
- https://malware-families-catalog.systemhelpdesk.com/defensive/downloader-dropper-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.trojan
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1566_001
- attack.t1105
- attack.t1055_001
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: mediumTier 3 Attribution Fingerprint Rule (High Fidelity)
Deep signature matching distinctive operational fingerprints and payload characteristics.
rule MALWARE_WIN_URSNIFDROPPER_T3_ATTRIBUTION {
meta:
description = "Tier 3 Attribution Fingerprint: Heuristic detection for Ursnifdropper 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 = "ursnifdropper" 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.
- Sever network connectivity for the flagged endpoint to terminate persistent command-and-control (C2) communication channels and stop Ursnifdropper from retrieving secondary stage payloads.
- Capture process memory triage to detect and terminate malicious threads injected by Ursnifdropper into legitimate system processes such as explorer.exe or svchost.exe.
- Audit Windows Registry Run keys (HKCU\Software\Microsoft\Windows\CurrentVersion\Run) and Task Scheduler entries to locate and purge Ursnifdropper persistence hooks.
- Deploy updated enterprise EDR detection signatures and conduct an out-of-band endpoint scan to isolate dropped binaries and staged payloads.
- Rotate all credentials, domain user passwords, and session cookies active on the system during the Ursnifdropper execution timeframe.
What to Avoid
Common mistakes during response to this family that can destroy evidence, spread the infection, or worsen recovery.
- Do not assume the incident is resolved simply because an antivirus tool removed the initial Ursnifdropper dropper; always verify that secondary payloads and persistence hooks have been eradicated.
- Avoid logging in with Domain Admin or privileged credentials on a machine suspected of running Ursnifdropper until memory triage is complete.
- Do not delay host isolation; automated lateral movement and credential dumping can occur within minutes of initial execution.
References & External Analysis
- Search "ursnifdropper" on VirusTotal (External Analysis)
- Search "ursnifdropper" on Any.Run (Sandbox Sandbox)
- Search "ursnifdropper" on MalwareBazaar (Malware Samples)
Frequently Asked Questions
What is Ursnifdropper and what threat category does it belong to?
Ursnifdropper is classified as a Trojan. Documented across security telemetry, it is engineered to execute unauthorized operations, establish persistent footholds on target endpoints, and facilitate malicious campaigns targeting enterprise and individual environments.
How does Ursnifdropper establish persistence and evade defensive controls?
Ursnifdropper typically establishes persistence through registry run keys, scheduled tasks, or service installations, while evading signature-based antivirus solutions through code obfuscation, memory injection, or anti-analysis sandbox checks.
What are the essential incident response steps for mitigating a Ursnifdropper compromise?
Security teams responding to Ursnifdropper should immediately isolate affected endpoints from the network, perform memory triage to capture volatile forensic artifacts, audit registry and startup persistence mechanisms, revoke exposed user credentials, and restore systems from verified, clean backups.
What secondary payloads and staging behaviors are commonly associated with TrojanDropper.Ursnif?
TrojanDropper.Ursnif frequently operates as a loader or dropper designed to establish a foothold before downloading and executing secondary high-impact malware payloads. Depending on the threat actor's objectives, these dropped modules can range from ransomware and banking injects to modular infostealers and remote management backdoors.
How can security operations teams effectively detect and hunt for TrojanDropper.Ursnif across enterprise endpoints?
Defenders should hunt for TrojanDropper.Ursnif by deploying behavioral endpoint detection and response (EDR) rules that monitor suspicious process spawning (such as cmd.exe or powershell.exe spawned from office documents or temporary directories), anomalous outbound network connections from non-browser binaries, and unauthorized modifications to Windows Run keys and scheduled task registries.
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.
Protect Your Network Against Trojans
Want to prevent Ursnifdropper and similar threats from compromising your organization? Read our comprehensive defensive guide: Banking Trojan Protection for Businesses.
📣 Threat Intel Correction or Update?
Notice an outdated IOC, unlisted alias, or disputed attribution? Threat researchers are invited to propose an update on GitHub or contact the SystemHelpDesk research desk. All community revisions are credited in our public CHANGELOG.
Machine-readable
Get this profile as JSON: https://malware-families-catalog.systemhelpdesk.com/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.