MEDUSALOCKER Ransomware Gang: 4 New Victims Posted — Manufacturing & Hospitality Targeting Analysis with Detection Rules

Classification: TLP:CLEAR | Report Date: 2026-09-13 | Source: Live .onion leak site monitoring via ransomware.live

Executive Summary

Dark web monitoring of the MEDUSALOCKER leak site has identified 4 new victim postings in a single 24-hour window (2026-09-12), spanning manufacturing, construction, and hospitality sectors across China, the United Arab Emirates, the United States, and India. This synchronized posting pattern is consistent with a batch-detonation campaign, indicating the affiliates likely compromised these organizations weeks earlier and are now executing the extortion phase in parallel.

Organizations running VMware vCenter, Cisco FMC, Check Point gateways, or ConnectWise ScreenConnect should treat this bulletin as an immediate patch-and-hunt trigger: multiple CVEs recently added to the CISA KEV with confirmed ransomware usage map directly to MEDUSALOCKER's historical initial access playbook.

Threat Actor Profile — MEDUSALOCKER

Known Toolset

• Lateral movement: PsExec, WMI, SMB administrative shares, stolen RDP credentials
• Credential access: Mimikatz variants, LSASS dumping, browser credential theft
• Staging/Exfil: Rclone and WinSCP to attacker-controlled cloud storage or FTP endpoints
• Defense evasion: Batch scripts to kill backup/database/security services, disabling Windows Defender via registry or PowerShell, clearing event logs

Current Campaign Analysis

Recent Victim Postings (Leak Site — 2026-09-12)

Sector Targeting

Manufacturing dominates this wave (2 of 4 victims, 50%), consistent with MEDUSALOCKER's long-standing preference for industrial and mid-market manufacturing firms — organizations that historically combine high operational downtime sensitivity (strong payment pressure) with legacy OT-adjacent Windows environments, flat networks, and slower patch cadence. The hospitality victim (a resort property in India) and the US construction firm round out a classic MEDUSALOCKER victimology profile: mid-market services businesses with lean IT staff and internet-facing remote access infrastructure.

Geographic Concentration

The CN / AE / US / IN spread indicates opportunistic rather than regionally focused targeting — affiliates are compromising whatever perimeter foothold is available globally, then posting in batches. This is characteristic of an affiliate-driven RaaS model rather than a directed campaign.

Victim Profile

• Size range: Small-to-mid-market enterprises (estimated 50–500 employees)
• Estimated revenue: $5M–$150M annually, based on sector norms (regional metal fabrication, specialty construction contracting, boutique hospitality)
• Common denominator: Organizations likely to carry cyber-insurance but unlikely to operate 24/7 SOC coverage — the RaaS "sweet spot"

Posting Frequency / Escalation

Four victims posted within a single day, with no postings in the preceding monitoring window, signals batch extortion: affiliates detonated or completed exfiltration on multiple networks in parallel, then released the victim list simultaneously to maximize psychological pressure and leak-site visibility. Expect follow-on data dumps over the next 72–168 hours for victims who refuse to engage.

Probable Initial Access — CVE Correlation

The following CISA KEV entries (all confirmed for ransomware use) align tightly with MEDUSALOCKER's historical perimeter-exploitation tradecraft and are the most probable entry vectors for this wave:

• CVE-2026-59310 — VMware vCenter Path Traversal (KEV 2026-08-18): vCenter compromise is a ransomware force multiplier — control of the virtualization layer enables mass VM encryption and destruction of snapshot-based recovery in a single action. Manufacturing victims running virtualized ERP/MES stacks are prime targets.
• CVE-2026-20316 — Cisco FMC Hard-coded Password (KEV 2026-07-29): Firewall management plane compromise yields both initial access and persistent visibility into the victim's defensive posture.
• CVE-2026-50751 — Check Point Security Gateway Improper Authentication (IKEv1) (KEV 2026-06-08): Direct VPN gateway exploitation — MEDUSALOCKER's most consistent historical entry vector.
• CVE-2024-1708 — ConnectWise ScreenConnect Path Traversal (KEV 2026-04-28): RMM abuse for hands-on intrusion; affiliates use legitimate RMM tooling to blend in with admin activity.
• CVE-2026-50751-adjacent note — CVE-2026-48027 (Nx Console) (KEV 2026-05-27): Supply-chain/developer tooling vector; relevant if victims run in-house software operations.

Analytic assessment (moderate confidence): The CN and AE manufacturing victims were most likely breached via perimeter VPN/firewall exploitation (CVE-2026-50751, CVE-2026-20316), while the US construction victim profile strongly suggests RMM or RDP-based access.

Detection Engineering

The following detections target MEDUSALOCKER's documented TTP chain: perimeter exploitation → credential theft → PsExec/WMI lateral movement → exfiltration staging → shadow copy deletion → encryption.

---
title: MedusaLocker Ransomware - Shadow Copy Deletion and Recovery Sabotage
id: 8f3a1c2e-7b4d-4e1a-9c6f-medusa000001
status: production
description: Detects vssadmin/wmic/bcdedit abuse consistent with MedusaLocker pre-encryption recovery sabotage. MedusaLocker affiliates routinely delete Volume Shadow Copies and disable boot recovery before detonation.
author: Security Arsenal Threat Intel
date: 2026/09/13
references:
  - https://securityarsenal.com/darkside
logsource:
  category: process_creation
  product: windows
detection:
  selection_vssadmin:
    Image|endswith: '\vssadmin.exe'
    CommandLine|contains:
      - 'delete shadows'
      - 'Delete Shadows'
  selection_wmic_shadow:
    Image|endswith: '\wmic.exe'
    CommandLine|contains: 'shadowcopy'
    CommandLine|contains:
      - 'delete'
      - 'call delete'
  selection_bcdedit:
    Image|endswith: '\bcdedit.exe'
    CommandLine|contains:
      - 'recoveryenabled no'
      - 'bootstatuspolicy ignoreallfailures'
  condition: 1 of selection_*
falsepositives:
  - Legitimate backup software operations
  - System administrators performing storage maintenance
level: critical
tags:
  - attack.impact
  - attack.t1490
---
title: MedusaLocker Lateral Movement - PsExec Service Execution
id: 8f3a1c2e-7b4d-4e1a-9c6f-medusa000002
status: production
description: Detects PsExec-style remote service installation and execution used by MedusaLocker affiliates for mass ransomware deployment across domain-joined hosts.
author: Security Arsenal Threat Intel
date: 2026/09/13
logsource:
  product: windows
  service: system
detection:
  selection_service:
    EventID: 7045
    Service_File_Name|contains:
      - 'PSEXESVC'
      - '\ADMIN$\'
      - 'PSEXEC'
  selection_remcom:
    EventID: 7045
    Service_Name|contains:
      - 'RemComSvc'
      - 'csexecsvc'
  condition: selection_service or selection_remcom
falsepositives:
  - Legitimate administrative software deployment tools (SCCM, PDQ)
  - IT administration using PsExec intentionally
level: high
tags:
  - attack.lateral_movement
  - attack.t1021.002
  - attack.t1569.002
---
title: MedusaLocker Data Staging - Rclone or WinSCP Exfiltration Indicators
id: 8f3a1c2e-7b4d-4e1a-9c6f-medusa000003
status: production
description: Detects execution of Rclone, WinSCP, or similar file transfer utilities from non-standard paths, a hallmark of MedusaLocker pre-encryption data exfiltration to attacker-controlled cloud storage.
author: Security Arsenal Threat Intel
date: 2026/09/13
logsource:
  category: process_creation
  product: windows
detection:
  selection_rclone:
    Image|endswith: '\rclone.exe'
    CommandLine|contains:
      - 'copy'
      - 'sync'
      - 'move'
  selection_winscp:
    Image|endswith:
      - '\winscp.exe'
      - '\WinSCP.com'
    CommandLine|contains:
      - '/command'
      - 'put'
      - 'synchronize'
  selection_suspicious_path:
    Image|contains:
      - '\AppData\Local\Temp\'
      - '\ProgramData\'
      - '\Users\Public\'
      - '\Windows\Temp\'
  condition: (selection_rclone or selection_winscp) or (selection_suspicious_path and (selection_rclone or selection_winscp))
falsepositives:
  - IT-managed Rclone backup jobs (allowlist by hash and scheduled task)
  - Legitimate WinSCP usage by administrators
level: high
tags:
  - attack.exfiltration
  - attack.t1567.002
  - attack.t1105

Microsoft Sentinel — Pre-Detonation Hunt Query

Hunt for the full MedusaLocker pre-encryption chain: suspicious admin-share writes followed by remote service creation and mass file renames within a 4-hour window.

// MedusaLocker Pre-Detonation Hunt: lateral movement -> service install -> encryption behavior
// Lookback: 7 days. Tune the AdminShareWrite threshold for your environment.
let Lookback = 7d;
let Window = 4h;
let SuspiciousServiceInstall =
    SecurityEvent
    | where TimeGenerated >= ago(Lookback)
    | where EventID == 7045
    | where ServiceFileName has_any ("PSEXESVC", "ADMIN$", "RemComSvc", "csexecsvc")
        or ServiceName has_any ("PSEXESVC", "RemComSvc")
    | summarize ServiceInstalls = count(), Services = make_set(ServiceName, 10)
        by Computer, Account, bin(TimeGenerated, 1h);
let AdminShareWrites =
    SecurityEvent
    | where TimeGenerated >= ago(Lookback)
    | where EventID == 5145
    | where Share_Name has_any ("\\\\*\\ADMIN$", "\\\\*\\C$")
    | where RelativeTargetName endswith ".exe" or RelativeTargetName endswith ".bat" or RelativeTargetName endswith ".ps1"
    | summarize DroppedBinaries = make_set(RelativeTargetName, 20), WriteCount = count()
        by Computer, Account = SubjectAccount, bin(TimeGenerated, 1h);
let ShadowCopyAbuse =
    SecurityEvent
    | where TimeGenerated >= ago(Lookback)
    | where EventID == 4688
    | where (Process has "vssadmin.exe" and CommandLine has "delete shadows")
        or (Process has "bcdedit.exe" and CommandLine has_any ("recoveryenabled", "bootstatuspolicy"))
    | project VssTime = TimeGenerated, Computer, Account, CommandLine;
SuspiciousServiceInstall
| join kind=inner AdminShareWrites on Computer, Account
| join kind=leftouter ShadowCopyAbuse on Computer
| extend PreDetonationScore = WriteCount + ServiceInstalls + iif(isnotempty(VssTime), 10, 0)
| where PreDetonationScore >= 3
| project TimeGenerated, Computer, Account, ServiceInstalls, Services, WriteCount, DroppedBinaries, CommandLine, PreDetonationScore
| order by PreDetonationScore desc;

Rapid Response Script — Shadow Copy & Persistence Enumeration

Run on suspected-compromised hosts or via your EDR's live response to catch MedusaLocker pre-detonation staging.

# MedusaLocker Rapid Triage Script - Security Arsenal
# Checks: shadow copy state, suspicious scheduled tasks (7d), new services, exposed RDP
# Run as Administrator. Output: console + C:\IR\MedusaTriage_<host>_<date>.log

$OutDir = "C:\IR"
New-Item -ItemType Directory -Path $OutDir -Force | Out-Null
$Log = Join-Path $OutDir ("MedusaTriage_{0}_{1}.log" -f $env:COMPUTERNAME, (Get-Date -Format 'yyyyMMdd_HHmm'))
Start-Transcript -Path $Log -Force

Write-Host "=== [1] Volume Shadow Copy Status ===" -ForegroundColor Cyan
$Shadows = Get-CimInstance Win32_ShadowCopy -ErrorAction SilentlyContinue
if (-not $Shadows) {
    Write-Host "[ALERT] NO shadow copies found - possible vssadmin deletion (MedusaLocker pre-encryption behavior)" -ForegroundColor Red
    wevtutil qe System "/q:*[System[(EventID=7036)]]" /f:text /c:20 | Select-String -Pattern "Volume Shadow Copy"
} else {
    $Shadows | Select-Object InstallDate, DeviceObject | Format-Table -AutoSize
}

Write-Host "=== [2] Scheduled Tasks Created/Modified in Last 7 Days ===" -ForegroundColor Cyan
Get-ScheduledTask | ForEach-Object {
    $info = $_ | Get-ScheduledTaskInfo -ErrorAction SilentlyContinue
    [PSCustomObject]@{
        TaskName   = $_.TaskName
        TaskPath   = $_.TaskPath
        Author     = $_.Author
        Date       = $_.Date
        LastRun    = $info.LastRunTime
        Action     = ($_.Actions | ForEach-Object { $_.Execute }) -join '; '
    }
} | Where-Object { $_.Date -gt (Get-Date).AddDays(-7) -and $_.TaskPath -notlike '\Microsoft*' } |
    Format-Table -AutoSize -Wrap

Write-Host "=== [3] Services Installed in Last 7 Days (7045) ===" -ForegroundColor Cyan
Get-WinEvent -FilterHashtable @{LogName='System'; Id=7045; StartTime=(Get-Date).AddDays(-7)} -ErrorAction SilentlyContinue |
    Select-Object TimeCreated, @{n='Service';e={$_.Properties[0].Value}}, @{n='Binary';e={$_.Properties[1].Value}} |
    Format-Table -AutoSize -Wrap

Write-Host "=== [4] RDP Exposure & Recent Failed Logons (Brute Force Indicator) ===" -ForegroundColor Cyan
$RdpEnabled = (Get-ItemProperty 'HKLM:\SYSTEM\CurrentControlSet\Control\Terminal Server' -Name fDenyTSConnections).fDenyTSConnections
Write-Host ("RDP Enabled (0=yes): {0}" -f $RdpEnabled)
Get-WinEvent -FilterHashtable @{LogName='Security'; Id=4625; StartTime=(Get-Date).AddDays(-1)} -ErrorAction SilentlyContinue |
    Where-Object { $_.Message -match 'Logon Type:\s+(3|10)' } |
    Group-Object -Property @{e={ if ($_.Message -match 'Source Network Address:\s+(\S+)') { $Matches[1] } }} |
    Sort-Object Count -Descending | Select-Object -First 10 Count, Name | Format-Table -AutoSize

Write-Host "=== [5] Exfil Tool Artifacts (rclone/winscp) ===" -ForegroundColor Cyan
$SearchPaths = @("$env:ProgramData", "$env:TEMP", "$env:PUBLIC", "C:\Users")
foreach ($p in $SearchPaths) {
    Get-ChildItem -Path $p -Recurse -Include 'rclone.exe','rclone.conf','winscp.exe','WinSCP.ini' -ErrorAction SilentlyContinue |
        Select-Object FullName, CreationTime, LastWriteTime
}

Stop-Transcript
Write-Host "Triage complete. Log: $Log" -ForegroundColor Green

Incident Response Priorities

T-Minus Detection Checklist (Before Encryption Fires)

MedusaLocker's dwell window gives defenders 7–21 days of detectable activity. Hunt for:

1. Perimeter anomalies — New VPN/firewall admin logons from unusual geographies or ASN; vCenter logins from non-jump-host sources (CVE-2026-59310 exploitation artifact).
2. Credential access — LSASS memory access events (Sysmon Event ID 10), Mimikatz-style sekurlsa strings in memory, abnormal DCSync (Event 4662 with replication GUIDs).
3. Discovery bursts — net group "Domain Admins" /domain, nltest /dclist, mass port scans (Sysmon Event ID 3 spikes) from a single internal host.
4. Staging — New rclone/WinSCP binaries in %ProgramData% or %Temp%; large outbound transfers (>5GB) to unfamiliar cloud/FTP endpoints over 24–72h.
5. Recovery sabotage — vssadmin delete shadows, bcdedit modifications, backup service stops (Veeam, Windows Backup, SQL VSS Writer). This is your last reliable tripwire — typically fires minutes-to-hours before detonation.
6. Mass deployment — Simultaneous Event 7045 service installs across multiple hosts; PsExec connections to ADMIN$ from a single source machine.

Assets This Gang Prioritizes for Exfiltration

Based on leak-site data published against past manufacturing/services victims:

• Finance: accounting databases, payroll records, bank details, tax filings
• Contracts & legal: customer/vendor agreements, NDAs, litigation files
• HR/PII: employee records, identity documents, benefits data (regulatory leverage)
• Engineering/IP (manufacturing-specific): CAD files, BOMs, process documentation, MES/ERP exports
• Email archives of executives and finance staff (used for negotiation pressure and follow-on BEC)

Containment Actions — Ordered by Urgency

1. Isolate at the switch/EDR level — Network-quarantine every host showing staging or sabotage indicators. Do NOT wait for confirmation of encryption.
2. Disable compromised perimeter devices — Force-reset VPN/firewall appliance credentials; if CVE-2026-50751 or CVE-2026-20316 exposure is confirmed, take the management interface offline pending patch.
3. Kill the identity layer — Reset all Domain Admin, service account, and KRBTGT (twice) credentials; revoke active sessions and tokens; disable the suspect initial-access account.
4. Protect backups immediately — Verify backup infrastructure is segmented/immutable and that backup admin credentials are separate from AD. MedusaLocker explicitly hunts Veeam and network-attached backup repositories.
5. Block exfil egress — Emergency egress filtering on FTP/SFTP and unsanctioned cloud storage domains at the proxy/firewall.
6. Preserve evidence before rebooting — Capture memory and triage images from the patient-zero host; MedusaLocker affiliates clear event logs on detonation.
7. Engage IR counsel early — Double extortion means a data-breach determination (and regulatory clock) may already be running before encryption occurs.

Hardening Recommendations

Immediate (24 Hours)

• Patch or mitigate all five KEV entries on this page — prioritizing internet-facing systems: Check Point gateways (CVE-2026-50751), Cisco FMC (CVE-2026-20316), VMware vCenter (CVE-2026-59310), and any ConnectWise ScreenConnect instances (CVE-2024-1708). If patching is impossible within 24h, remove management interfaces from internet exposure entirely.
• Audit internet-facing RDP — Confirm no RDP is directly exposed; enforce VPN + MFA gating. MedusaLocker has brute-forced exposed RDP since 2019.
• Deploy the Sigma rules above and run the Sentinel hunt query across the last 14 days, not just 7.
• Verify shadow copies and offline backups exist and are restorable — test one restore today.
• Block rclone/WinSCP execution for non-admin users via AppLocker/WDAC or EDR policy.

Short-Term (2 Weeks)

• Segment the network — Manufacturing victims consistently suffer flat-network mass encryption. Isolate OT/MES segments, restrict SMB/RDP between workstation VLANs, and place backup infrastructure on a separate, firewall-governed segment.
• Phishing-resistant MFA everywhere — FIDO2 for VPN, RDP gateways, vCenter, and remote admin tooling. Password-only remote access is the single most common root cause in this gang's intrusions.
• Deploy 24/7 detection coverage — MEDUSALOCKER's target profile (mid-market, no overnight SOC) means detonation frequently occurs on weekends. Managed detection and response closes the exact gap this gang exploits.
• Application control on servers — WDAC/AppLocker policies that deny unsigned binaries in %Temp%, %ProgramData%, and user-writable directories on servers block the affiliate tooling drop pattern.
• Harden backup architecture — Move to immutable/object-lock backup storage with credentials fully separated from Active Directory; alert on any VSS deletion event as a Sev-1.
• Tabletop the double-extortion scenario — Legal, comms, and executive teams should rehearse a "data published on leak site" scenario, not just an encryption scenario.

Security Arsenal continuously monitors ransomware leak sites, affiliate chatter, and KEV-confirmed exploitation trends. Organizations in manufacturing, construction, or hospitality — particularly those with exposed VPN or vCenter infrastructure — should treat this campaign as an active threat and initiate threat hunting immediately.

Related Resources

Security Arsenal Incident Response Managed SOC & MDR Services AlertMonitor Threat Detection From The Dark Side Intel Hub