Bang5Mai
Table of Contents
Overview
Bang5mai (identified across endpoint security databases and threat intelligence feeds under signatures including Trojan:Win32/Bang5mai, Backdoor:Win32/Bang5mai, and Trojan.Bang5mai) is a covert Windows backdoor and targeted initial access implant active since 2017. Typically deployed in spear-phishing campaigns delivering weaponized Office documents or embedded in trojanized developer toolkits, Bang5mai establishes persistent access through scheduled tasks and registry autostart keys. Upon installation, the malware collects detailed host metadata—including system architecture, domain memberships, user privileges, and running security processes—and communicates with external C2 servers over HTTPS. Bang5mai features a modular payload execution engine that allows remote operators to execute arbitrary command-line strings, manipulate host files and directories, inject secondary DLL payloads into legitimate Windows processes (such as svchost.exe), and stage lateral movement tools across corporate Active Directory environments.
Known aliases
Threat reports may refer to this family under multiple names:
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: Trojan:Win32/Bang5Mai.A · Backdoor:Win32/Bang5Mai.B
MITRE ATT&CK Techniques
This family has been observed using the following ATT&CK techniques: T1059.003 · T1055 · T1071.001 · T1547.001 · T1082
Tactical Mitigations
Based on the techniques used by this family, consider the following defensive strategies:
- T1059.003: Restrict execution of Windows Command Shell (cmd.exe) and block unauthorized batch scripts.
- T1071.001: Implement web filtering and SSL/TLS inspection to detect malicious command and control (C2) traffic hiding in HTTP/HTTPS.
MITRE D3FEND™ Defensive Countermeasures
Defensive techniques mapped to counter the offensive tradecraft observed in this family (via the MITRE D3FEND matrix):
| D3FEND ID | Countermeasure Name | Tactic | Countered ATT&CK | Defensive Guidance |
|---|---|---|---|---|
D3-PIAD | Process Injection Analysis & Detection | Detect | T1055 | Monitor cross-process thread creation (CreateRemoteThread) and asynchronous procedure calls (QueueUserAPC). |
D3-PBA | Process Spawn Analysis | Detect | T1059.003 | Inspect command-line arguments and anomalous parent-child relationships spawning from cmd.exe. |
D3-WAF | Web Content Filtering & Inspection | Filter | T1071.001 | Block newly registered domains (NRDs) and inspect HTTP Host and URI headers for known C2 profiles. |
D3-SDA | System Discovery Analysis | Detect | T1082 | Alert on rapid enumerations of systeminfo, hostname, and registry hardware trees in short intervals. |
D3-RPM | Registry Persistence Monitoring | Detect | T1547.001 | Audit and restrict write privileges to user and machine-level Registry Run/RunOnce keys using Endpoint Privilege Management. |
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:
Tier 1 Primitive Artifact Rule (Fast Triage)
Matches raw strings and file markers. Vulnerable to binary repacking and simple obfuscation.
rule MALWARE_WIN_BANG5MAI_T1_ARTIFACT {
meta:
description = "Tier 1 Primitive Artifact: Raw string matches for Bang5Mai"
tier = "T1 - Primitive Artifact"
confidence = "Low-Medium (Fast Triage)"
author = "SystemHelpdesk Threat Research Desk"
date = "2026-10-14"
strings:
$s1 = "bang5mai" ascii wide nocase
$s2 = "trojan:win32/bang5mai" ascii wide nocase
$s3 = "backdoor:win32/bang5mai" ascii wide nocase
$s4 = "trojan.bang5mai" ascii wide nocase
$s5 = "win32/bang5mai" ascii wide nocase
$s6 = "trojan:win32/bang5mai.a" ascii wide nocase
condition:
uint16(0) == 0x5a4d and any of them
}Tier 2 Behavioral Context Rule (Process Chains & Sigma)
Tracks parent-child process anomalies and suspicious scripting telemetry. Resilient against file renames.
title: SystemHelpDesk Detection - Bang5mai (Backdoor) Execution & Triage
id: 8e0a597c-3f64-5d67-9149-a178524d1fdf
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
with the Bang5mai malware family. Detects proxy execution, reflective DLL loading,
and remote command injection associated with modular enterprise backdoors.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/bang5mai
- https://malware-families-catalog.systemhelpdesk.com/defensive/backdoor-rat-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.backdoor
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1059_003
- attack.t1055
- attack.t1071_001
- attack.t1547_001
- attack.t1082
logsource:
category: process_creation
product: windows
detection:
selection_process:
Image|endswith:
- \powershell.exe
- \cmd.exe
- \rundll32.exe
- \regsvr32.exe
CommandLine|contains:
- DownloadString
- IEX(
- '/s /n /u /i:'
- sc create
- start-process
condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: highTier 3 Attribution Fingerprint Rule (High Fidelity)
Deep signature matching distinctive operational fingerprints and payload characteristics.
rule MALWARE_WIN_BANG5MAI_T3_ATTRIBUTION {
meta:
description = "Tier 3 Attribution Fingerprint: Heuristic detection for Bang5Mai 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 = "bang5mai" 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
}References & External Analysis
- Microsoft Defender Threat Encyclopedia - Trojan:Win32/Bang5mai
- Trend Micro Threat Encyclopedia - Backdoor.Win32.Bang5mai
- Search "bang5mai" on VirusTotal (External Analysis)
- Search "bang5mai" on Any.Run (Sandbox Sandbox)
- Search "bang5mai" on MalwareBazaar (Malware Samples)
Frequently Asked Questions
What is Trojan:Win32/Bang5mai?
Bang5mai is a modular Windows backdoor that provides unauthorized remote access, executes commands, and stages lateral movement in enterprise networks.
How does Bang5mai achieve persistence on Windows systems?
It creates hidden scheduled tasks and writes entries to the Windows CurrentVersion\Run registry key to ensure execution on system reboot.
What host information is gathered by Bang5mai?
It collects computer hostnames, active domain memberships, user privilege levels, network adapter configurations, and installed antivirus software.
How does Bang5mai evade detection during command execution?
It injects payload worker threads into legitimate Windows system processes like svchost.exe and communicates over encrypted HTTPS channels.
What are the recommended incident response actions for Bang5mai?
Isolate the infected endpoint from the network, terminate unauthorized injected processes, remove persistence tasks, and reset corporate domain credentials.
What are the main symptoms of a Bang5Mai infection?
Symptoms of Bang5Mai can include unexpected system slowness, unauthorized outbound network traffic to unknown IP addresses, disabled security software, and suspicious background processes running from AppData or Temp directories.
Protect Your Network Against Backdoors
Want to prevent Bang5Mai and similar threats from compromising your organization? Read our comprehensive defensive guide: Backdoor & RAT Protection for Businesses.
📣 Threat Intel Correction or Update?
Notice an outdated IOC, unlisted alias, or disputed attribution? Threat researchers are invited to propose an update on GitHub or contact the SystemHelpDesk research desk. All community revisions are credited in our public CHANGELOG.
Machine-readable
Get this profile as JSON: https://malware-families-catalog.systemhelpdesk.com/api/bang5mai.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.