Mepaow

Overview

Mepaow (cataloged in antivirus vendor databases and threat intelligence feeds under detections including Trojan:Win32/Mepaow, Worm.Win32.MEPAOW, and Trojan.Mepaow) is a hybrid Windows trojan and worm active since 2012. Engineered to maintain persistent access across enterprise networks and consumer workstations, Mepaow spreads via infected removable USB media (leveraging autorun.inf scripts and deceptive shortcut files) as well as malicious email attachments. Once active, Mepaow copies itself into system directories under randomized filenames, registers autostart keys under Windows CurrentVersion\Run, and injects surveillance threads into legitimate operating system processes. It records active user windows, hooks keyboard inputs to capture credentials, and establishes beaconing sessions with attacker-controlled command servers over HTTP to download secondary malicious binaries.

Known aliases

Threat reports may refer to this family under multiple names:

• Trojan:Win32/Mepaow
• Worm.Win32.MEPAOW
• Trojan.Mepaow
• Win32/Mepaow

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: Win32 Worm & Surveillance Hybrid Toolkits

Known Derivatives & Downstream Variants: Mepaow.Aa · Mepaow.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:

• T1105: Implement network intrusion detection systems (NIDS) and host-based firewalls to block unauthorized inbound or outbound file transfers.
• 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.

• 5a6b7c8d9e0f1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b1c2d3e4f5a6b
• 6b7c8d9e0f1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b1c2d3e4f5a6b7c

Delivery vectors

• usb_setup.exe
• document_photo.exe

Persistence mechanisms

• HKCU\Software\Microsoft\Windows\CurrentVersion\Run\MepaowUpdate
• %AppData%\Mepaow\mepaow.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_MEPAOW_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Mepaow"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "mepaow" ascii wide nocase
        $s2 = "trojan:win32/mepaow" ascii wide nocase
        $s3 = "worm.win32.mepaow" ascii wide nocase
        $s4 = "trojan.mepaow" ascii wide nocase
        $s5 = "win32/mepaow" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Mepaow (Trojan) Execution & Triage
id: 8bfd25e0-8ab8-5aae-9c06-191d40a71abd
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Mepaow 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/mepaow
- https://malware-families-catalog.systemhelpdesk.com/defensive/downloader-dropper-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.trojan
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1091
- attack.t1056_001
- attack.t1547_001
- attack.t1105
- attack.t1055
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_MEPAOW_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Mepaow 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 = "mepaow" 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 to prevent Mepaow from downloading and executing its secondary payloads (e.g., ransomware).
2. Audit the Windows Task Scheduler and Registry Run keys to identify and remove the Mepaow persistence mechanisms.
3. Review firewall and proxy logs to identify the C2 domains Mepaow attempted to contact, and block them enterprise-wide.
4. Capture a live memory image (RAM dump) to extract the injected Mepaow modules and identify the secondary payloads.

What to Avoid

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

1. Do not close an incident simply because the initial Mepaow dropper was quarantined; always verify if secondary payloads were downloaded.
2. Avoid relying solely on manual file deletion, as the injected processes will likely just recreate the dropped binaries.

References & External Analysis

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

Frequently Asked Questions

Related Threats (Category: Trojan)

Explore other documented threats in the same operational category:

• Dumpy
• Luminorat
• Redsip
• Trjgen
• Dnschange
• Lockpos
• Transmit
• Informer

Machine-readable

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