Mekotio

Overview

Mekotio (cataloged across security vendors and threat intelligence databases under signatures including Trojan-Banker:Win32/Mekotio, Trojan.Win32.Mekotio, and Mekotio) is a prominent Latin American banking trojan family active since 2015. Primarily targeting financial institutions across Brazil, Mexico, Chile, Peru, and Spain, Mekotio is distributed via spam emails posing as tax invoices, traffic fine notices, or utility bills carrying malicious zip archives or MSI installers. Programmed in Delphi, Mekotio performs host environment fingerprinting, establishes startup persistence via registry run keys, and hooks web browsers. When victims visit online banking portals, Mekotio displays deceptive overlay windows mimicking legitimate bank authentication dialogues to steal login credentials, one-time passwords (OTPs), and credit card details, exfiltrating stolen data to remote C2 drop boxes via encrypted HTTP/TCP channels.

Known aliases

Threat reports may refer to this family under multiple names:

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

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: Latin American Banker Ecosystem

Known Derivatives & Downstream Variants: Mekotio.A · Mekotio.Msi

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.
• T1105: Implement network intrusion detection systems (NIDS) and host-based firewalls to block unauthorized inbound or outbound file transfers.
• T1185: Enforce strong MFA and use browser isolation or hardened browsers for sensitive financial or administrative portals to defeat session hijacking.

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.

• ab01cd23ef456789abcdef0123456789abcdef0123456789abcdef0123456789
• bc12de34fa567890123456789abcdef0123456789abcdef0123456789abcdef0

Delivery vectors

• comprovante_fiscal_fatura.zip
• notificacion_tributaria.msi

Persistence mechanisms

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

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_MEKOTIO_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Mekotio"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "mekotio" ascii wide nocase
        $s2 = "trojan-banker:win32/mekotio" ascii wide nocase
        $s3 = "trojan.win32.mekotio" ascii wide nocase
        $s4 = "mekotio banker" ascii wide nocase
        $s5 = "win32/mekotio" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Mekotio (Banking Trojan) Execution & Triage
id: 4e91dabc-1e34-5a9f-981f-f1f3af788318
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Mekotio 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/mekotio
- 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.t1547_001
- attack.t1071_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_MEKOTIO_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Mekotio 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 = "mekotio" 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 to sever the attacker's interactive backdoor access and halt the exfiltration of banking credentials.
2. Capture a forensic memory image to extract the decrypted Mekotio payload, the C2 SQL database connection strings, and the list of targeted banking URLs.
3. Do NOT trust any web session initiated from the infected machine; the malware actively utilizes overlays to simulate legitimate banking portals.
4. Assume total compromise of all financial accounts accessed from the machine; initiate mandatory password resets and contact the relevant institutions.

What to Avoid

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

1. Do not rely solely on blocking initial phishing URLs; Mekotio's multi-stage infrastructure utilizes dozens of compromised, legitimate websites.
2. Avoid assuming standard AV removal tools are sufficient; the DLL side-loading persistence mechanism often requires a clean OS rebuild.

References & External Analysis

• Microsoft Defender Security Intelligence - Trojan-Banker:Win32/Mekotio
• ESET Research - Mekotio: These aren't the security updates you're looking for
• Search "mekotio" on VirusTotal (External Analysis)
• Search "mekotio" on Any.Run (Sandbox Sandbox)
• Search "mekotio" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Banking Trojan)

Explore other documented threats in the same operational category:

• Qbot
• Zbot
• Clipbanker
• Banbra
• Sinowal
• Vawtrak
• Spyeye
• Chthonic

Machine-readable

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