Bancos

Overview

Bancos (cataloged across security vendors and threat intelligence databases under signatures including Trojan-Banker.Win32.Bancos, Trojan:Win32/Bancos, and Win32/Bancos) is an enduring and pervasive family of Brazilian banking trojans active since 2003. Specifically targeting customers of Brazilian, Latin American, and Portuguese financial institutions, Bancos is distributed primarily through targeted phishing emails with malicious links, weaponized documents, and fake banking security certificate downloads. Upon execution, Bancos hooks Windows APIs and web browser processes, continuously monitoring open browser window titles for strings associated with major banking portals (including Banco do Brasil, Bradesco, Itaú, Santander, and Caixa Econômica Federal). When a victim navigates to a targeted bank, Bancos overlays deceptive, pixel-perfect fake authentication windows or keypad capture forms designed to harvest account numbers, electronic passwords, and multi-factor transaction authentication numbers (TANs). The stolen credentials are immediately exfiltrated to remote C2 drop sites via HTTP or SMTP. Bancos also actively modifies the Windows hosts file and installs fake digital certificates to conduct man-in-the-browser attacks while disabling local security tools like Warsaw and Trusteer Rapport.

Known aliases

Threat reports may refer to this family under multiple names:

• Trojan-Banker.Win32.Bancos
• Trojan:Win32/Bancos
• Win32/Bancos
• Bancos Banker

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: Brazilian Banker Ecosystem

Known Derivatives & Downstream Variants: Bancos.A · Bancos.Q · Bancos.Delphi

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.
• 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):

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.

• 4b5c6d7e8f90123456789abcdef0123456789abcdef0123456789abcdef01234
• 5c6d7e8f90123456789abcdef0123456789abcdef0123456789abcdef012345

Delivery vectors

• comprovante_pagamento_banco.exe
• modulo_seguranca_bancaria.scr

Persistence mechanisms

• HKCU\Software\Microsoft\Windows\CurrentVersion\Run\BancosUpdater

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_BANCOS_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Bancos"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "bancos" ascii wide nocase
        $s2 = "trojan-banker.win32.bancos" ascii wide nocase
        $s3 = "trojan:win32/bancos" ascii wide nocase
        $s4 = "win32/bancos" ascii wide nocase
        $s5 = "bancos banker" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Bancos (Banking Trojan) Execution & Triage
id: 6d1ad8d1-c728-566c-95f9-b0f757c340ae
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Bancos 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/bancos
- 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_002
- attack.t1056_002
- attack.t1555_003
- attack.t1112
- 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_BANCOS_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Bancos 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 = "bancos" 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. Immediately isolate the endpoint from the network to halt the active credential harvesting and prevent the attacker from maintaining a live session with the bank.
2. Assume all financial credentials used on the machine are compromised; initiate mandatory password resets and contact relevant banking institutions immediately.
3. Capture a forensic memory image to extract the active Bancos configuration, identifying exactly which financial institutions were targeted.
4. Due to the aggressive credential harvesting, a complete, clean rebuild of the operating system is the most secure remediation.

What to Avoid

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

1. Do not allow the user to type any passwords or access sensitive portals while the machine is infected.
2. Avoid relying solely on basic AV removal, as Bancos frequently updates its persistence mechanisms and drops secondary payloads.

References & External Analysis

• Microsoft Defender Security Intelligence - Trojan-Banker:Win32/Bancos
• Kaspersky Securelist - The Evolution of Brazilian Banking Trojans
• Search "bancos" on VirusTotal (External Analysis)
• Search "bancos" on Any.Run (Sandbox Sandbox)
• Search "bancos" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Banking Trojan)

Explore other documented threats in the same operational category:

• Zusy
• Sinowal
• Zbot
• Gozi
• Clipbanker
• Shylock
• Banbra
• Alien

Machine-readable

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