Healthcare Ransomware Alert: Defending Against Encryption-Based Attacks on AZ & TX Clinics

---
title: Healthcare Ransomware - Volume Shadow Copy Deletion
id: 8a2c8a9d-1f4c-4e9a-8b3c-1d2f3b4c5d6e
status: experimental
description: Detects attempts to delete Volume Shadow Copies using vssadmin or wmic, a critical precursor to ransomware encryption in healthcare environments.
references:
  - https://attack.mitre.org/techniques/T1490/
author: Security Arsenal
date: 2024/05/23
tags:
  - attack.impact
  - attack.t1490
logsource:
  category: process_creation
  product: windows
detection:
  selection:
    Image|endswith:
      - '\vssadmin.exe'
      - '\wmic.exe'
    CommandLine|contains:
      - 'delete shadows'
      - 'shadowcopy delete'
  condition: selection
falsepositives:
  - Legitimate system administration tasks (rare in clinic environments)
level: critical
---
title: Ransomware Payload - Mass Encryption CLI Indicators
id: 9b3d9b0e-2g5d-5f0b-9c4d-2e3g4c5d6e7f
status: experimental
description: Detects command-line arguments consistent with common ransomware families attempting to encrypt drives recursively.
references:
  - https://attack.mitre.org/techniques/T1486/
author: Security Arsenal
date: 2024/05/23
tags:
  - attack.impact
  - attack.t1486
logsource:
  category: process_creation
  product: windows
detection:
  selection_generic:
    CommandLine|contains:
      - '-m encrypt'
      - 'add_extension'
  selection_files:
    CommandLine|contains:
      - '*.locked'
      - '*.encrypted'
      - '--crypt'
  condition: 1 of selection*
falsepositives:
  - Legitimate backup encryption utilities
level: high

// Hunt for Ransomware Precursors: Shadow Copy Deletion
// Focuses on processes deleting system backups, a high-fidelity signal for ransomware preparation.
DeviceProcessEvents
| where Timestamp > ago(7d)
| where FileName in~ ("vssadmin.exe", "wmic.exe", "powershell.exe")
| where ProcessCommandLine has_any ("delete shadows", "shadowcopy delete", "shadowcopy /delete", "Remove-WBBackupSet")
| project Timestamp, DeviceName, AccountName, FileName, ProcessCommandLine, InitiatingProcessFileName, InitiatingProcessAccountName
| order by Timestamp desc

-- Hunt for processes attempting to delete Volume Shadow Copies or modify backup configs
SELECT Pid, Name, Exe, Username, CommandLine, CreateTime
FROM pslist()
WHERE Name =~ 'vssadmin' OR Name =~ 'wmic'
  AND CommandLine =~ '(?i)delete.*shadow'

-- Hunt for recently created ransomware notes (common extensions)
SELECT FullPath, Size, Mtime, Btime
FROM glob(globs="/*/*.txt", root="C:\")
WHERE FileName =~ '(?i)(readme|restore|recover|files|decrypt|instructions)'
  AND Mtime < now() - 24h

# IR Triaging: Isolate Host and Check for Encryption Activity
# Requires Administrator Privileges

Write-Host "[+] Starting Emergency IR Isolation..." -ForegroundColor Cyan

# 1. Disable Network Adapters to stop lateral movement and C2 exfiltration
Try {
    Get-NetAdapter | Where-Object { $_.Status -eq 'Up' } | Disable-NetAdapter -Confirm:$false
    Write-Host "[!] Network adapters DISABLED. Host isolated." -ForegroundColor Red
} Catch {
    Write-Host "[-] Failed to disable network adapters: $_" -ForegroundColor Yellow
}

# 2. Check for Critical Process Activity (VSS Deletion)
Write-Host "[+] Checking for VSS Deletion processes..." -ForegroundColor Cyan
$vssProcess = Get-WinEvent -FilterHashtable @{LogName='Security'; ID=4688} -MaxEvents 1000 -ErrorAction SilentlyContinue |
    Where-Object { $_.Message -match 'vssadmin' -and $_.Message -match 'delete' } |
    Select-Object -First 1

if ($vssProcess) {
    Write-Host "[!] ALERT: Evidence of VSS Shadow Copy deletion found in Security Logs." -ForegroundColor Red
}

# 3. Identify new files with encrypted extensions (Last 24h)
Write-Host "[+] Scanning for encrypted file extensions..." -ForegroundColor Cyan
$extensions = @('.locked', '.encrypted', '.cryptolocker', '.micro', '.locky')
$encFiles = Get-ChildItem -Path "C:\" -Recurse -Include $extensions -ErrorAction SilentlyContinue |
    Where-Object { $_.LastWriteTime -gt (Get-Date).AddHours(-24) }

if ($encFiles.Count -gt 5) {
    Write-Host "[!] CRITICAL: $($encFiles.Count) encrypted files found in last 24 hours. Ransomware confirmed." -ForegroundColor Red
}

Write-Host "[+] Triage Complete. Do NOT reboot if memory forensics is required." -ForegroundColor Green