Mabezat
Table of Contents
Overview
Mabezat (extensively documented in threat research and anti-malware databases as Worm:Win32/Mabezat, Virus:Win32/Mabezat.B, and W32.Mabezat) is a landmark polymorphic worm and parasitic file infector first identified in 2007. Engineered to spread aggressively across local networks, removable USB drives, and email systems, Mabezat infects Portable Executable (PE) files by appending its polymorphic malicious code to the last section of executables. In addition to executable infection, Mabezat recursively traverses local and mapped drives, searching for user documents and media files (.doc, .pdf, .xls, .jpg), encrypting them with a custom XOR/RC4 algorithm, and appending the .dlz or .chm extension. It distributes copies of itself disguised inside self-extracting RAR archives, creates autorun.inf files on removable media, and harvests email addresses from Windows Address Books to send infectious messages via direct SMTP connections.
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: Worm:Win32/Mabezat.A · Virus:Win32/Mabezat.B · Virus.Win32.Mabezat.C
MITRE ATT&CK Techniques
This family has been observed using the following ATT&CK techniques: T1091 · T1080 · T1566.001 · T1486 · T1057
Tactical Mitigations
Based on the techniques used by this family, consider the following defensive strategies:
- 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):
| D3FEND ID | Countermeasure Name | Tactic | Countered ATT&CK | Defensive Guidance |
|---|---|---|---|---|
D3-RMC | Removable Media Access Control | Harden | T1091 | Enforce Group Policy settings disabling Windows autorun and block execution permissions on removable USB storage media. |
D3-FAED | File Alteration Early Detection | Detect | T1486 | Deploy canary files and monitor mass rename/encryption I/O spikes to terminate ransomware threads immediately. |
D3-FS | File Sandboxing (Attachment Detonation) | Isolate | T1566.001 | Detonate macro-enabled documents, ISOs, and password-protected archives inside an isolated hypervisor. |
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_MABEZAT_T1_ARTIFACT {
meta:
description = "Tier 1 Primitive Artifact: Raw string matches for Mabezat"
tier = "T1 - Primitive Artifact"
confidence = "Low-Medium (Fast Triage)"
author = "SystemHelpdesk Threat Research Desk"
date = "2026-10-14"
strings:
$s1 = "mabezat" ascii wide nocase
$s2 = "worm:win32/mabezat" ascii wide nocase
$s3 = "virus:win32/mabezat.b" ascii wide nocase
$s4 = "virus.win32.mabezat.b" ascii wide nocase
$s5 = "win32/mabezat" ascii wide nocase
$s6 = "w32.mabezat" ascii wide nocase
$s7 = "worm.win32.mabezat" 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 - Mabezat (Worm) Execution & Triage
id: ba75e96d-216d-5da7-b47b-b5aae59cf110
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
with the Mabezat 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/mabezat
- 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.worm
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1091
- attack.t1080
- attack.t1566_001
- attack.t1486
- attack.t1057
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: mediumTier 3 Attribution Fingerprint Rule (High Fidelity)
Deep signature matching distinctive operational fingerprints and payload characteristics.
rule MALWARE_WIN_MABEZAT_T3_ATTRIBUTION {
meta:
description = "Tier 3 Attribution Fingerprint: Heuristic detection for Mabezat 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 = "mabezat" 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 - Worm:Win32/Mabezat.B
- Symantec Threat Report - W32.Mabezat Technical Profile
- Kaspersky Securelist - Virus.Win32.Mabezat.b In-Depth
- Search "mabezat" on VirusTotal (External Analysis)
- Search "mabezat" on Any.Run (Sandbox Sandbox)
- Search "mabezat" on MalwareBazaar (Malware Samples)
Frequently Asked Questions
What is Worm:Win32/Mabezat?
Mabezat is a historic polymorphic worm and virus that infects Windows executable files, encrypts personal documents, and spreads via USB drives, network shares, and email.
How does Mabezat propagate through removable USB storage?
It copies its executable to the root of connected USB flash drives and writes a malicious autorun.inf configuration to launch automatically when inserted.
What happens to documents infected or targeted by Mabezat?
Mabezat encrypts user documents (.doc, .pdf, .xls) and renames them with extensions like .dlz or .chm, making them inaccessible without decryption routines.
How does Mabezat infect other executable files?
It appends polymorphic viral code to the final section of existing PE executables, redirecting the entry point to execute the virus before returning control to the host program.
How can systems be disinfected from a Mabezat infection?
Disable Windows Autorun/Autoplay, boot into Safe Mode to clean infected PE files with specialized disinfection tools, and restore encrypted documents from offline backups.
How do I remove the Mabezat Worm from Windows?
Manual removal of Mabezat is highly discouraged as it may leave persistence mechanisms intact. We recommend disconnecting the device from the internet and utilizing a professional incident response service or enterprise-grade EDR software to conduct a full forensic sweep.
Is Mabezat a virus or a Worm?
Mabezat is classified as a Worm. Unlike traditional viruses that infect files, modern malware like Mabezat typically operates as a standalone payload designed to compromise systems, steal data, or deploy secondary stage implants.
What are the main symptoms of a Mabezat infection?
Symptoms of Mabezat 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 Worms
Want to prevent Mabezat and similar threats from compromising your organization? Read our comprehensive defensive guide: Worm & Virus Protection.
📣 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/mabezat.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.