Blouiroet
Table of Contents
Overview
Blouiroet (identified in antimalware telemetry under signatures including Ransom:Win32/Blouiroet, Trojan-Ransom.Win32.Blouiroet, and Trojan.Blouiroet) is a destructive crypto-ransomware and extortion threat active since 2016. Infiltrating endpoints primarily through phishing email campaigns containing weaponized office documents and exploit kit redirections, Blouiroet initiates rapid host reconnaissance upon execution. It terminates database, backup, and antimalware processes via taskkill, releasing open file locks across local drives and network shares. Blouiroet traverses directory trees, encrypting documents, spreadsheets, databases, source code, and archives using AES-256 with an embedded RSA public key. It executes vssadmin commands to purge Volume Shadow Copies, modifies desktop wallpaper to display an extortion notice, and demands cryptocurrency payment in exchange for a decryption utility.
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: Ransom:Win32/Blouiroet.A · Ransom:Win32/Blouiroet.B
MITRE ATT&CK Techniques
This family has been observed using the following ATT&CK techniques: T1486 · T1490 · T1547.001 · T1082 · T1071.001
Tactical Mitigations
Based on the techniques used by this family, consider the following defensive strategies:
- 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-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-FAED | File Alteration Early Detection | Detect | T1486 | Deploy canary files and monitor mass rename/encryption I/O spikes to terminate ransomware threads immediately. |
D3-VSS | Volume Shadow & Snapshot Hardening | Harden | T1490 | Block execution of vssadmin.exe and wmic shadowcopy delete; maintain air-gapped immutable backup repositories. |
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_BLOUIROET_T1_ARTIFACT {
meta:
description = "Tier 1 Primitive Artifact: Raw string matches for Blouiroet"
tier = "T1 - Primitive Artifact"
confidence = "Low-Medium (Fast Triage)"
author = "SystemHelpdesk Threat Research Desk"
date = "2026-10-14"
strings:
$s1 = "blouiroet" ascii wide nocase
$s2 = "ransom:win32/blouiroet" ascii wide nocase
$s3 = "trojan-ransom.win32.blouiroet" ascii wide nocase
$s4 = "trojan.blouiroet" ascii wide nocase
$s5 = "win32/blouiroet" ascii wide nocase
$s6 = "ransom:win32/blouiroet.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 - Blouiroet (Ransomware) Execution & Triage
id: b89d94e4-2ca8-5efe-8de9-d50d8c68e853
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
with the Blouiroet malware family. Detects volume shadow copy deletion, boot status
tampering, and recovery inhibition characteristic of modern ransomware operations.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/blouiroet
- 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.ransomware
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1486
- attack.t1490
- attack.t1547_001
- attack.t1082
- attack.t1071_001
logsource:
category: process_creation
product: windows
detection:
selection_process:
Image|endswith:
- \vssadmin.exe
- \wmic.exe
- \wbadmin.exe
- \bcdedit.exe
CommandLine|contains:
- delete shadows
- shadowcopy delete
- resize shadowstorage
- recoveryenabled no
- ignoreallfailures
condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: criticalTier 3 Attribution Fingerprint Rule (High Fidelity)
Deep signature matching distinctive operational fingerprints and payload characteristics.
rule MALWARE_WIN_BLOUIROET_T3_ATTRIBUTION {
meta:
description = "Tier 3 Attribution Fingerprint: Heuristic detection for Blouiroet 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 = "blouiroet" 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 - Ransom:Win32/Blouiroet
- Trend Micro Threat Encyclopedia - Ransom.Win32.Blouiroet
- Search "blouiroet" on VirusTotal (External Analysis)
- Search "blouiroet" on Any.Run (Sandbox Sandbox)
- Search "blouiroet" on MalwareBazaar (Malware Samples)
Frequently Asked Questions
What is Ransom:Win32/Blouiroet?
Blouiroet is a crypto-ransomware family that encrypts personal documents with AES-256 and demands cryptocurrency ransom for decryption.
How does Blouiroet disable Windows recovery options?
It executes vssadmin to purge Volume Shadow Copies and disables Windows automated startup recovery using bcdedit.
What file types are encrypted by Blouiroet?
It targets business spreadsheets, documents, databases, developer source code, archives, and multimedia files.
How does Blouiroet spread into computer systems?
It spreads via malicious email attachments containing weaponized macros, compromised software downloads, and exploit kits.
What defense effectively protects against Blouiroet ransomware?
Maintain offline immutable backups, enable Controlled Folder Access in Microsoft Defender, and enforce strict execution policies.
How do I remove Blouiroet from Windows?
Manual removal of Blouiroet 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.
What are the main symptoms of a Blouiroet infection?
Symptoms of Blouiroet 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 Ransomwares
Want to prevent Blouiroet and similar threats from compromising your organization? Read our comprehensive defensive guide: Ransomware Containment & Incident Response.
📣 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/blouiroet.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.