Classification: TLP:CLEAR | Publication Date: 2026-09-29 | Source: ransomware.live leak-site monitoring (single-source for some listings — see Sourcing & Verification) | Nature of data: Unverified threat-actor claims

MEDUSALOCKER Claims 4 New Listings Across Finance, Government, Agriculture and Energy — Detection & Hunt Brief

Executive Summary

On 2026-09-28, the MEDUSALOCKER ransomware leak site listed four organizations: PKSF — Palli Karma-Sahayak Foundation (Financial Services, BD), Juntadeandalucia (Government & Defense, ES), Premiumfruits (Agriculture and Food Production, ES), and ATCO Ltd (Energy & Utilities, CA). These are threat-actor claims, not confirmed breaches. All four listings are currently single-source observations in our collection pipeline, so defenders should treat this as an early-warning signal for sector and geography exposure rather than proof of compromise.

The operational concern is the cross-sector mix: financial services, government/defense administration, food production, and energy/utilities are all high-impact environments where outage tolerance is low and data sensitivity is high. Organizations matching these profiles should prioritize internet edge validation, RDP/VPN authentication review, pre-encryption staging hunts, and backup integrity checks. CVE discussion below is sector-level exposure hypothesis only; we have no evidence tying any named organization to a specific CVE.

Sourcing & Verification

• 0 of 4 listings were independently observed by a second leak-site crawler; 4 of 4 appear on a single source only.
• Inclusion reflects MEDUSALOCKER’s claim and is not confirmation of a breach, intrusion, data theft, encryption, or active incident at any named organization.
• A named organization may dispute the listing. A denial is likewise not proof the criminal claim is false; disclosure obligations vary by jurisdiction and incident type, and not every incident is reportable, so neither silence nor denial settles the question.
• Security Arsenal will publish corrections and welcomes contact from any named organization at security@securityarsenal.com.

Threat Actor Profile — MEDUSALOCKER

MEDUSALOCKER is a long-running ransomware operation first widely observed in 2019 and should not be confused with the separate Medusa ransomware brand. Reporting over multiple years describes it as an affiliate-enabled/RaaS-like model with periods of relatively closed recruitment, using a leak site to pressure victims through double extortion: data theft claims plus encryption or threatened encryption.

Typical tradecraft associated with MEDUSALOCKER intrusions includes: phishing and malicious documents for initial execution; brute-force or exposed RDP; compromised VPN or remote access credentials; exploitation of internet-facing services when opportunity aligns; use of legitimate admin tooling such as PsExec, WMI, PowerShell, scheduled tasks and batch scripts for lateral movement; disabling recovery options such as Volume Shadow Copies; and staging archives before exfiltration. Ransom demands vary by victim revenue and perceived ability to pay, historically ranging from tens of thousands to multi-million-dollar equivalents. Dwell time is commonly days to a few weeks, with faster detonation possible where access is purchased or credentials are already valid.

Current Campaign Analysis

Sectors named in this batch: Financial Services; Government & Defense; Agriculture and Food Production; Energy & Utilities. Countries named: BD, ES, CA. The postings cluster tightly on 2026-09-28, suggesting either a single leak-site publication wave or delayed public posting after separate intrusion timelines.

Victim profile appears economically and operationally significant rather than purely opportunistic micro-business targeting: a development-finance foundation in Bangladesh, a large Spanish public-sector entity name reference, a Spanish food producer, and a Canadian energy/utilities firm. Revenue estimates vary widely by sector, but the common denominator is critical service continuity and regulated or sensitive data.

Posting frequency in the last 100 collected postings is low for this batch window: 4 recent listings, all dated 2026-09-28. That can indicate a small synchronized dump, a crawler visibility gap, or a temporary lull; it should not be read as reduced capability. Escalation pattern to watch: republication with proof packs, countdown timers, partial file-tree screenshots, and follow-on listing of additional entities in the same supply chain.

CVE relevance is hypothesis only: MEDUSALOCKER has historically benefited from exposed remote access and edge weaknesses, and the current CISA KEV set includes sector-relevant exposure classes: CVE-2026-20316 Cisco Secure FMC hard-coded password, CVE-2026-50751 Check Point IKEv1 improper authentication, CVE-2026-59310 VMware vCenter path traversal, CVE-2026-63077 JetBrains TeamCity deserialization, and CVE-2026-48027 Nx Console embedded malicious code. We do not attribute initial access for PKSF, Juntadeandalucia, Premiumfruits, or ATCO Ltd to any CVE.

Detection Engineering

---
title: MEDUSALOCKER Pre-Encryption RDP or VPN Anomaly Followed by Admin Tool Execution
id: 8f6f1d2c-4c91-4a1f-9d2c-medusalocker001
status: experimental
description: Detects suspicious remote logon patterns followed by PsExec/WMI/PowerShell execution consistent with ransomware pre-staging.
author: Security Arsenal
date: 2026/09/29
logsource:
  product: windows
  service: security
detection:
  selection_logon:
    EventID: 4624
    LogonType:
      - 3
      - 10
  selection_exec:
    EventID: 4688
    NewProcessName|endswith:
      - '\psexec.exe'
      - '\wmic.exe'
      - '\powershell.exe'
      - '\cmd.exe'
  condition: selection_logon and selection_exec
falsepositives:
  - Administrative remote management
level: high
tags:
  - attack.initial_access
  - attack.lateral_movement
  - attack.t1078
  - attack.t1021.001
  - attack.t1569.002
---
title: MEDUSALOCKER Shadow Copy Deletion or Backup Tampering
id: 9b2a77d1-2de4-4f92-a911-medusalocker002
status: experimental
description: Identifies vssadmin, wbadmin, bcdedit or PowerShell commands commonly used before detonation to inhibit recovery.
author: Security Arsenal
date: 2026/09/29
logsource:
  category: process_creation
  product: windows
detection:
  selection_img:
    Image|endswith:
      - '\vssadmin.exe'
      - '\wbadmin.exe'
      - '\bcdedit.exe'
      - '\powershell.exe'
  selection_cmd:
    CommandLine|contains:
      - 'delete shadows'
      - 'resize shadowstorage'
      - 'delete catalog'
      - 'recoveryenabled no'
      - 'Get-WmiObject Win32_Shadowcopy'
  condition: selection_img and selection_cmd
falsepositives:
  - Backup administration
level: critical
tags:
  - attack.impact
  - attack.t1490
---
title: MEDUSALOCKER Data Staging Archive and Cloud Exfil Utility
id: 71d44c90-7cf6-4f55-bd90-medusalocker003
status: experimental
description: Finds compression plus possible exfil utilities such as rclone, 7z, WinRAR, curl or mega tooling near sensitive directories.
author: Security Arsenal
date: 2026/09/29
logsource:
  category: process_creation
  product: windows
detection:
  selection_tool:
    Image|endswith:
      - '\rclone.exe'
      - '\7z.exe'
      - '\rar.exe'
      - '\curl.exe'
      - '\megacmd.exe'
  selection_paths:
    CommandLine|contains:
      - '\finance'
      - '\hr'
      - '\backup'
      - '\users'
      - '\shared'
      - 'copy '
      - 'sync '
      - 'archive'
  condition: selection_tool and selection_paths
falsepositives:
  - Legitimate backup or migration jobs
level: high
tags:
  - attack.collection
  - attack.exfiltration
  - attack.t1560
  - attack.t1567

// Hunt: remote logon -> admin tooling -> shadow-copy tampering within 24h
let WindowStart = ago(7d);
let Remote = SecurityEvent
| where TimeGenerated >= WindowStart
| where EventID == 4624 and LogonType in (3,10)
| project LogonTime=TimeGenerated, Computer, Account, IpAddress, LogonType;
let Proc = SecurityEvent
| where TimeGenerated >= WindowStart
| where EventID == 4688
| where NewProcessName has_any (@"\psexec.exe",@"\wmic.exe",@"\powershell.exe",@"\cmd.exe",@"\vssadmin.exe",@"\wbadmin.exe",@"\bcdedit.exe",@"\rclone.exe",@"\7z.exe",@"\rar.exe")
| project ProcTime=TimeGenerated, Computer, Account, NewProcessName, CommandLine;
Remote
| join kind=inner Proc on Computer, Account
| where ProcTime between (LogonTime .. LogonTime+24h)
| summarize FirstLogon=min(LogonTime), LastProc=max(ProcTime), Tools=make_set(NewProcessName), Commands=make_set(CommandLine) by Computer, Account, IpAddress
| where array_length(Tools) >= 2 or Commands has_any ("delete shadows","recoveryenabled no","rclone","psexec")
| order by FirstLogon asc;

# Rapid MEDUSALOCKER exposure and pre-staging check - run elevated on Windows servers/endpoints
$since = (Get-Date).AddDays(-7)
Write-Host "== RDP listeners ==" ; Get-NetTCPConnection -State Listen -LocalPort 3389 -ErrorAction SilentlyContinue | Select LocalAddress,LocalPort,OwningProcess
Write-Host "== Recent scheduled tasks ==" ; Get-ScheduledTask | Where-Object {$_.Date -gt $since -or $_.LastRunTime -gt $since} | Select TaskName,TaskPath,Date,LastRunTime
Write-Host "== Shadow copies ==" ; vssadmin list shadows 2>$null ; Get-WmiObject Win32_ShadowCopy -ErrorAction SilentlyContinue | Select ID,InstallDate,DeviceObject
Write-Host "== Suspicious recent binaries in user/temp paths ==" ; Get-ChildItem "$env:TEMP","$env:USERPROFILE\Downloads","C:\Users\Public" -Recurse -ErrorAction SilentlyContinue | Where-Object {$_.LastWriteTime -gt $since -and $_.Extension -in '.exe','.dll','.ps1','.bat'} | Select FullName,LastWriteTime,Length
Write-Host "== Failed logons 4625 top IPs ==" ; Get-WinEvent -FilterHashtable @{LogName='Security';Id=4625;StartTime=$since} -ErrorAction SilentlyContinue | ForEach-Object {$_.Properties[19].Value} | Group-Object | Sort Count -Descending | Select -First 20 Name,Count

Incident Response Priorities

T-minus detection checklist before encryption fires: unusual 4624 type 3/10 bursts from new IPs; repeated 4625 then success on VPN/RDP; new local admin or service account; PsExec service creation 7045; WMI process call create; PowerShell encoded commands; mass file opens under shares; vssadmin/wbadmin/bcdedit execution; sudden archive creation; rclone/curl/7z near finance, HR, backup or engineering shares; EDR tamper attempts; backup job failures outside maintenance windows.

Critical assets this gang historically prioritizes for extortion value: finance and payroll data, HR/PII, legal contracts, board communications, backup catalogs, domain controllers, virtualization management, file servers, ERP exports, customer databases, OT-adjacent documentation, and identity stores that enable re-entry.

Containment ordered by urgency: 1) isolate suspected hosts from network without powering off if volatile evidence matters; 2) disable or reset exposed remote access and revoke suspect sessions/tokens; 3) block egress to unknown cloud storage and newly registered domains; 4) protect backups by taking immutable copies offline and pausing replication from possibly poisoned sources; 5) reset credentials in tiered order starting with domain admin, VPN, service accounts and backup admins; 6) preserve logs from VPN, firewall, EDR, AD, DHCP and hypervisors before rotation; 7) engage legal/comms and regulator counsel early because claims may trigger notification analysis even when unverified.

Hardening Recommendations

Immediate 24h: enforce MFA on VPN, RDP gateways, OWA and remote admin planes; block direct internet RDP and require brokered access; patch or mitigate KEV items at the edge and management plane, especially Cisco Secure FMC, Check Point gateways, vCenter and TeamCity where present; disable NTLM where feasible; alert on vssadmin delete shadows and bcdedit recoveryenabled changes; deny user-writable temp execution; lock down PsExec with application control; verify immutable backup isolation and test one restore.

Short-term 2 weeks: implement tiered identity and just-in-time admin; segment backup, virtualization management, OT-adjacent and core finance networks; deploy egress filtering with explicit allowlists for cloud storage; centralize logs for VPN/AD/EDR/DNS into Sentinel with 90-day hot retention; add canary files and deceptive shares; establish leak-site monitoring escalation for brand, subsidiaries and key suppliers; run tabletop for double-extortion decisioning including denial, negotiation, regulatory and customer-notification paths.

Related Resources

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