Gozi

Overview

Trojan:Win32/Gozi (also universally tracked as ISFB and the Ursnif family tree) is one of the most historically significant, resilient banking trojans in computer history. First authored around 2007 by Russian national Nikita Kuzmin, Gozi was specifically designed to intercept online banking credentials, digital certificates, and wire transfer credentials from commercial banks. In 2010, Kuzmin was arrested in the United States and subsequently pleaded guilty in the Southern District of New York (SDNY), while co-conspirators Deniss Calovskis ('Miami') of Latvia and Mihail Sevrovs of Romania were arrested and extradited. Following Kuzmin's arrest, the complete Gozi source code leaked online around 2010, leading to a prolific ecosystem of independent criminal forks including ISFB v2/v3, Dreambot, IcedID, and GozNym. Gozi employs advanced API hooking in explorer.exe and browser processes (Internet Explorer, Firefox, Chrome), utilizing Tor-based or encrypted TLS C2 infrastructure with dynamic domain generation algorithms (DGA) to exfiltrate keystrokes, clipboard contents, and intercepted banking session cookies.

Known aliases

Threat reports may refer to this family under multiple names:

• Gozi
• ISFB
• Ursnif
• Trojan.Gozi
• Win32/Gozi
• Gozi-ISFB

Threat Actor Attribution

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

• Nikita Kuzmin (Author) High confidence
  Basis:
• Deniss Calovskis (Webinject Developer) High confidence
  Basis:
• Russian Cybercrime Underworld High confidence
  Basis:

Family Pedigree & Lineage

Malware authors regularly fork and iterate upon existing codebases. Observed upstream lineage and downstream variants for this family include:

Known Derivatives & Downstream Variants: Gozi V1 (2007) · Isfb V2.X (Leaked Code) · Dreambot · Goznym (Hybrid) · Icedid (Lineage)

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:

• T1056.001: Implement Endpoint Detection and Response (EDR) to monitor for suspicious API calls related to keystroke interception. Enforce Multi-Factor Authentication (MFA) to render stolen passwords useless.
• 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-2012-0158 — In-depth exploitation analysis and catalog intelligence (NIST NVD ↗).
• CVE-2017-0199 — In-depth exploitation analysis and catalog intelligence (NIST NVD ↗).
• CVE-2017-11882 — 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.

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.

• 1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef
• fedcba0987654321fedcba0987654321fedcba0987654321fedcba0987654321

Delivery vectors

• phishing_emails
• exploit_kits
• malvertising

Persistence mechanisms

• HKCU\Software\Microsoft\Windows\CurrentVersion\Run
• Registry Binary Storage

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_GOZI_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Gozi"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "gozi" ascii wide nocase
        $s2 = "gozi" ascii wide nocase
        $s3 = "isfb" ascii wide nocase
        $s4 = "ursnif" ascii wide nocase
        $s5 = "trojan.gozi" ascii wide nocase
        $s6 = "win32/gozi" ascii wide nocase
        $s7 = "gozi-isfb" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Gozi (Banking Trojan) Execution & Triage
id: 799ccdff-4802-5f81-b978-8d45641b7b30
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Gozi 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/gozi
- 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.t1185
- attack.t1055_001
- attack.t1555_003
- attack.t1071_001
- attack.t1566_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_GOZI_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Gozi 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 = "gozi" 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. Terminate suspicious browser injection threads and isolate affected accounting endpoints.
2. Revoke compromised digital certificates, banking cookies, and web session tokens.
3. Deploy endpoint detection agents capable of identifying API hooks in wininet.dll and ws2_32.dll.
4. Apply security updates for Microsoft Office equation editor vulnerability CVE-2017-11882.

What to Avoid

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

1. Do not input corporate banking credentials on workstations showing unauthorized browser extensions or strange certificate warnings.
2. Avoid opening macro-enabled Office files received from unknown or unverified vendors.
3. Never store digital banking private keys without hardware-token protection.

References & External Analysis

• US Department of Justice: Creator of Gozi Virus Convicted in Manhattan Federal Court
• CISA Alert: Ursnif/Gozi Banking Malware Technical Overview
• NIST National Vulnerability Database CVE-2017-11882
• Search "gozi" on VirusTotal (External Analysis)
• Search "gozi" on Any.Run (Sandbox Sandbox)
• Search "gozi" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Banking Trojan)

Explore other documented threats in the same operational category:

• Vawtrak
• Blackmoon
• Dridex
• A_311_Death
• Chthonic
• Goznym
• Shiotob
• Dreambot

Machine-readable

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