Ursnif

Overview

Ursnif (also widely known by its underlying codebase names Gozi and ISFB) is one of the most enduring and technically sophisticated banking trojans and modular stealers in cybercrime history. Originally authored around 2007 by Russian developer Nikita Kuzmin (who was later arrested and pled guilty in U.S. federal court), the malware was designed to intercept online banking credentials, hijack financial transactions, and conduct man-in-the-browser (MitB) webinjections against financial institutions worldwide. Following successive leaks of the Gozi and ISFB (v2) source code on underground hacking forums in 2014 and 2015, the malware fractured into multiple independently maintained variants, most notably Dreambot, IAuto, and SaLoad. Ursnif employs heavy multi-stage obfuscation, packing its loaders with custom crypters, executing code through process hollowing (typically injecting into explorer.exe or svchost.exe), and persisting across reboots using heavily obfuscated registry run keys or COM hijacking. Ursnif is particularly known for using image steganography, hiding its encrypted secondary configurations and C2 domain lists inside ordinary-looking BMP, GIF, and PNG image files hosted on compromised web servers. In contemporary operations, Ursnif has evolved beyond pure retail banking fraud, frequently serving as an enterprise access broker and loader for ransomware affiliate operations.

Known aliases

Threat reports may refer to this family under multiple names:

• Ursnif
• Gozi
• Gozi-ISFB
• ISFB
• Dreambot
• IAP
• SaLoad

Threat Actor Attribution

Attribution is probabilistic, not a science. Each link below states its confidence level and the evidence behind it.

• Nikita Kuzmin / Gozi Criminal Syndicate High confidence
  Basis: Originally engineered by Russian national Nikita Kuzmin (pled guilty in U.S. SDNY in 2013). Bulletproof hosting was managed by Mihai Paunescu (convicted and sentenced in 2023), and webinject modules were developed by Deniss Calovskis. Following the 2014 and 2015 public leaks of the ISFB source code, distinct cybercriminal groups spun off Dreambot and SaLoad variants. [source]

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: Gozi

Known Derivatives & Downstream Variants: Dreambot · Isfb · Saload

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:

• T1071.001: Implement web filtering and SSL/TLS inspection to detect malicious command and control (C2) traffic hiding in HTTP/HTTPS.
• T1185: Enforce strong MFA and use browser isolation or hardened browsers for sensitive financial or administrative portals to defeat session hijacking.
• 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):

Exploited Vulnerabilities (CVEs)

This malware family is documented weaponizing the following common vulnerabilities and exposures:

• CVE-2017-11882 — In-depth exploitation analysis and catalog intelligence (NIST NVD ↗).
• CVE-2017-0199 — In-depth exploitation analysis and catalog intelligence (NIST NVD ↗).
• CVE-2016-0189 — In-depth exploitation analysis and catalog intelligence (NIST NVD ↗).

Command & Control (C2) and Network Profile

How this family talks to its operators. C2 traffic can often identify a family even when its code and configuration are hard to analyse. Ports and patterns are historical and change between campaigns, so use them as hunting leads rather than block-only rules.

Network detection ideas

• Inspect HTTP traffic for image files (.png, .bmp, .gif) returning encrypted binary payloads instead of valid image headers
• Block and monitor traffic matching C2 IP indicators published in CISA alerts and abuse.ch Feodo Tracker
• Monitor for process injection anomalies where child processes connect outbound over TLS immediately following Microsoft Office document execution

Sources: CISA Advisory AA20-302A, Malpedia Ursnif/ISFB

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.

• a3b95764d7df7f73db17f18b3dcaecdf0e1fe6b77ae4b0d0092cce53df4a6138
• 0f6222bfa8952467d027e8529348d6132646d5ee3269b2d887349176ca0cf508
• 59b48c4cf667b9370cecb393d987d6eec08fdf569da89178bf7493a38ce3722b

Delivery vectors

• Spear-phishing emails containing macro-enabled XLS/DOC documents
• Weaponized RTF attachments exploiting CVE-2017-0199
• Equation Editor exploit documents weaponized with CVE-2017-11882

Persistence mechanisms

• Obfuscated registry Run keys under HKCU\Software\Microsoft\Windows\CurrentVersion\Run
• Process hollowing into explorer.exe, svchost.exe, or msiexec.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_URSNIF_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Ursnif"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "ursnif" ascii wide nocase
        $s2 = "ursnif" ascii wide nocase
        $s3 = "gozi" ascii wide nocase
        $s4 = "gozi-isfb" ascii wide nocase
        $s5 = "isfb" ascii wide nocase
        $s6 = "dreambot" ascii wide nocase
        $s7 = "iap" ascii wide nocase
        $s8 = "saload" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Ursnif (Banking Trojan) Execution & Triage
id: 472daafc-a73b-5d79-b2c3-4cdbb2a81024
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Ursnif malware family. Detects recon staging, certutil file payload staging,
  and web-inject process proxying characteristic of banking trojan initial loaders.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/ursnif
- https://malware-families-catalog.systemhelpdesk.com/defensive/banking-trojan-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.banking-trojan
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1566_001
- attack.t1055
- attack.t1185
- attack.t1071_001
- attack.t1547_001
logsource:
  category: process_creation
  product: windows
detection:
  selection_process:
    Image|endswith:
    - \svchost.exe
    - \explorer.exe
    - \msiexec.exe
    - \certutil.exe
    CommandLine|contains:
    - -urlcache
    - -split -f
    - ipconfig /all
    - route print
    - netstat -ano
  condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: high

rule MALWARE_WIN_URSNIF_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Ursnif 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 = "ursnif" 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 from the corporate network to prevent Ursnif from executing real-time Automated Transfer System (ATS) fraudulent transactions or web injections.
2. Revoke all active online banking sessions, treasury management credentials, and accounting administrator sessions accessed from the machine.
3. Analyze browser process memory (hooks on wininet.dll, ws2_32.dll, nspr4.dll) to detect and eradicate injected Ursnif fraud modules.
4. Notify internal financial compliance and partner banking institutions to place temporary fraud holds or elevated monitoring on relevant accounts.

What to Avoid

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

1. Do not permit financial transactions or banking portal access from any machine in the same broadcast domain until Ursnif network activity is cleared.
2. Avoid relying solely on antivirus scans, as banking trojans frequently hook browser API calls directly in user-mode memory.

References & External Analysis

• MITRE ATT&CK: Ursnif (S0386)
• CISA Advisory: CISA Alert AA20-302A (Top Routinely Exploited Vulnerabilities)
• Search "ursnif" on VirusTotal (External Analysis)
• Search "ursnif" on Any.Run (Sandbox Sandbox)
• Search "ursnif" on MalwareBazaar (Malware Samples)

North American Authority Advisory (CISA / NIST)

The Cybersecurity and Infrastructure Security Agency (CISA) has published an official US federal advisory on this family, which can be mapped to NIST Cybersecurity Framework (CSF) incident response controls: CISA Alert AA20-302A (Top Routinely Exploited Vulnerabilities) ↗

Frequently Asked Questions

Related Threats (Category: Banking Trojan)

Explore other documented threats in the same operational category:

• Icedid
• Tinba
• Snifula
• Dreambot
• Danabot
• Tinynuke
• Zbot
• Alien

Machine-readable

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