How to Protect Hospitals Against Inevitable Encryption-Based Cyber Incidents
Excerpt: Encryption-based attacks threaten patient safety. Learn how rehearsals, immutable backups, and defensive monitoring protect healthcare systems.
Introduction
In the healthcare sector, the question of ransomware is no longer "if," but "when." A recent discussion by a Chief Medical Information Officer highlights that encryption-based cyber incidents—essentially ransomware attacks—pose an existential threat to hospital operations. These attacks don't just encrypt data; they encrypt the systems required for life-saving care. For defenders, this means that traditional security postures must shift from pure prevention to a strategy of resilience, rehearsal, and rapid recovery.
Technical Analysis
Encryption-based attacks typically involve unauthorized access to the network, lateral movement to critical servers, and the deployment of malware that uses strong encryption (e.g., AES-256) to lock files on both endpoints and network shares. In a hospital environment, the attack surface includes Electronic Health Records (EHR), Picture Archiving and Communication Systems (PACS), and IoT medical devices.
The severity is critical. Unlike other industries where downtime means lost revenue, in healthcare, downtime can mean lost lives. The technical impact involves the mass encryption of databases and file shares, often coupled with the deletion of Volume Shadow Copies to prevent native recovery. Attackers exploit vulnerabilities in unpatched systems or rely on phishing to gain initial access.
Defensive Monitoring
To defend against these threats, security operations centers (SOCs) must have visibility into the precursors of encryption events. This includes detecting attempts to delete backups or the mass execution of encryption utilities.
SIGMA Rules
---
title: Deletion of Volume Shadow Copies via Vssadmin
id: 1a2b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: stable
description: Detects attempts to delete volume shadow copies using vssadmin.exe, a common technique used by ransomware to prevent recovery.
references:
- https://attack.mitre.org/techniques/T1490/
author: Security Arsenal
date: 2024/05/21
tags:
- attack.impact
- attack.t1490
logsource:
category: process_creation
product: windows
detection:
selection:
Image|endswith: '\vssadmin.exe'
CommandLine|contains: 'delete shadows'
falsepositives:
- System administration tasks
level: high
---
title: Inhibit System Recovery via BCDedit
id: f1e2d3c4-b5a6-7890-c1d2-e3f4a5b6c7d8
status: stable
description: Detects the use of bcdedit to disable recovery options or modify boot configuration, often used by ransomware to prevent system restoration.
references:
- https://attack.mitre.org/techniques/T1490/002/
author: Security Arsenal
date: 2024/05/21
tags:
- attack.impact
- attack.t1490.002
logsource:
category: process_creation
product: windows
detection:
selection:
Image|endswith: '\bcdedit.exe'
CommandLine|contains:
- 'recoveryenabled no'
- 'no'
falsepositives:
- Rare legitimate system recovery modifications
level: high
---
title: Mass File Encryption via Ransomware Tooling
id: a1b2c3d4-e5f6-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects the execution of processes often associated with file encryption or wiping activity on endpoints.
references:
- https://attack.mitre.org/techniques/T1486/
author: Security Arsenal
date: 2024/05/21
tags:
- attack.impact
- attack.t1486
logsource:
category: process_creation
product: windows
detection:
selection:
Image|endswith:
- '\cipher.exe'
- '\bitsadmin.exe'
CommandLine|contains:
- '/w'
- '/transfer'
falsepositives:
- Legitimate administrative disk wiping or file transfer
level: medium
KQL Queries
// Detect deletion of Volume Shadow Copies
DeviceProcessEvents
| where FileName in~ ("vssadmin.exe", "wmic.exe")
| where ProcessCommandLine contains "delete" and ProcessCommandLine contains "shadow"
| project Timestamp, DeviceName, FileName, ProcessCommandLine, InitiatingProcessFileName
// Hunt for suspicious PowerShell execution that might be ransomware related
DeviceProcessEvents
| where FileName == "powershell.exe"
| where ProcessCommandLine contains "Encrypt" or ProcessCommandLine contains "Invoke-AESEncryption"
| project Timestamp, DeviceName, ProcessCommandLine
Velociraptor VQL
-- Hunt for Ransom Notes on endpoints
SELECT FullPath, Size, Mtime
FROM glob(globs='C:\Users\**\*')
WHERE Name =~ '(?i)^(readme|restore|recover|files_encrypted|how_to_decrypt)\.(txt|html|hta|png)$'
LIMIT 50
-- Check for processes modifying VSS state
SELECT Pid, Name, CommandLine, Exe
FROM pslist()
WHERE Name =~ 'vssadmin' OR Name =~ 'wmic'
PowerShell Verification
<#
.SYNOPSIS
Checks the health and availability of Volume Shadow Copies (VSS).
.DESCRIPTION
This script queries the system for available VSS shadows to ensure backup mechanisms are not tampered with.
#>
Get-WmiObject -Class Win32_ShadowCopy | Select-Object DeviceObject, InstallDate, VolumeName, State
Remediation
- Conduct Regular Tabletop Exercises (TTX): As highlighted in the recent news, rehearsals are key. Simulate an encryption incident to test the speed of your identification, isolation, and recovery teams.
- Implement Immutable Backups: Ensure backups are offline or immutable (WORM storage) so they cannot be deleted or encrypted by attackers who compromise the network.
- Network Segmentation: Strictly segment medical devices (IoT) from the main IT network. If a workstation is encrypted, the impact on life-support systems must be isolated.
- Patch Management: Prioritize patching of critical vulnerabilities in internet-facing systems and remote access protocols (RDP, VPN).
- Disable Unused Protocols: Turn off SMBv1 and restrict the use of PowerShell WMI across the network unless necessary.
Related Resources
Security Arsenal Healthcare Cybersecurity AlertMonitor Platform Book a SOC Assessment healthcare Intel Hub
Is your security operations ready?
Get a free SOC assessment or see how AlertMonitor cuts through alert noise with automated triage.