Bancteian

Overview

Bancteian (cataloged across security vendors under signatures including Trojan:Win32/Bancteian, TrojanDownloader:Win32/Bancteian, and Trojan.Bancteian) is a specialized Windows trojan downloader and staging agent active since 2015. Closely associated with the Latin American Banload banking malware ecosystem, Bancteian is deployed as a stealth initial stager designed to compromise host systems and download complex secondary banking trojans (such as members of the Banker and Guildma families). Delivered primarily via spearphishing emails disguised as judicial notifications, unpaid utility invoices, or electronic tax documents, Bancteian arrives inside password-protected ZIP archives containing deceptive LNK files, VBScripts, or weaponized PDF documents. Upon execution, Bancteian deploys anti-sandbox sleep routines, interrogates host language settings and keyboard layouts to confirm geographical targets (frequently Brazil and other South American regions), and connects to remote C2 servers to fetch, decrypt, and execute secondary banking overlay trojans designed to steal online banking credentials.

Known aliases

Threat reports may refer to this family under multiple names:

• Trojan:Win32/Bancteian
• TrojanDownloader:Win32/Bancteian
• Win32/Bancteian
• Trojan.Bancteian

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: Banload Banking Trojan Family

Known Derivatives & Downstream Variants: Bancteian.A · Bancteian.B

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:

• T1056.004: Monitor for unauthorized keylogging, screen capturing, or web browser API hooking. Deploy EDR to detect API hooking.
• 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.

• 7c6d5e4f3a2b1c0d9e8f7a6b5c4d3e2f1a0b9c8d7e6f5a4b3c2d1e0f9a8b7c6d
• 3a2b1c0d9e8f7a6b5c4d3e2f1a0b9c8d7e6f5a4b3c2d1e0f9a8b7c6d5e4f3a2b

Delivery vectors

• notificacao_judicial.zip
• fatura_pendente.vbs

Persistence mechanisms

• HKCU\Software\Microsoft\Windows\CurrentVersion\Run\BancteianLoader
• %AppData%\Bancteian\bank_update.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_BANCTEIAN_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Bancteian"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "bancteian" ascii wide nocase
        $s2 = "trojan:win32/bancteian" ascii wide nocase
        $s3 = "trojandownloader:win32/bancteian" ascii wide nocase
        $s4 = "win32/bancteian" ascii wide nocase
        $s5 = "trojan.bancteian" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Bancteian (Downloader) Execution & Triage
id: b2726929-9e3b-507b-9d8c-fd7a76be5984
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Bancteian 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/bancteian
- https://malware-families-catalog.systemhelpdesk.com/defensive/ransomware-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.downloader
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1566_001
- attack.t1204_002
- attack.t1059_003
- attack.t1547_001
- attack.t1105
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: medium

rule MALWARE_WIN_BANCTEIAN_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Bancteian 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 = "bancteian" 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 exfiltration of banking credentials and prevent interactive MitB sessions.
2. Assist the user in immediately contacting their financial institutions to freeze accounts, block recent transactions, and reset all passwords.
3. Capture a live memory image (RAM dump) to extract the injected Bancteian DLLs and the downloaded web-inject configuration files.
4. Perform a clean OS rebuild; banking trojans establish deep, complex hooks in the browser that are extremely difficult to eradicate manually.

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 access any online banking or financial portals while the machine is infected.
2. Avoid rebooting the machine before capturing memory, as the critical web-inject configurations and stolen session tokens exist only in RAM.

References & External Analysis

• Microsoft Defender Security Intelligence - Trojan:Win32/Bancteian
• Trend Micro Threat Encyclopedia - Trojan.Win32.Banload
• Search "bancteian" on VirusTotal (External Analysis)
• Search "bancteian" on Any.Run (Sandbox Sandbox)
• Search "bancteian" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Downloader)

Explore other documented threats in the same operational category:

• Chapak
• Aim_Downloader
• Fraudrop
• Upatre
• Nymeria
• Banload
• Dofoil
• Reconyc

Machine-readable

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