Starr Insurance Ransomware Incident: Defensive Playbook for Encryption-Based Attacks

Starr Insurance (Starr Companies) has officially disclosed a "encryption-based cyber incident," confirming the industry's worst fears: a ransomware attack targeting the insurance sector. As an organization handling Protected Health Information (PHI) and sensitive financial data, the implications of this breach extend beyond mere operational downtime. The attack, reported to have involved data encryption and likely exfiltration, places the Personally Identifiable Information (PII) of countless individuals at risk.

For defenders, this is not a wake-up call—it is a confirmation of the active threat landscape targeting healthcare entities and their partners. Encryption-based attacks are rarely isolated events; they are the culmination of lateral movement, credential dumping, and privilege escalation. We must move beyond basic awareness and harden our environments against the specific TTPs (Tactics, Techniques, and Procedures) used in these campaigns.

Technical Analysis

The incident reported by Starr Insurance falls squarely into the category of a Ransomware/Breach event. While the specific strain of ransomware (e.g., LockBit, BlackCat/ALPHV, etc.) has not been explicitly disclosed in the initial report, the descriptors "encryption-based" and "data breach" provide a clear technical profile for defenders to hunt for.

• Attack Vector: Encryption-based attacks typically begin with initial access via phishing, exploiting public-facing vulnerabilities, or valid credentials obtained via initial access brokers. In the healthcare vertical, social engineering and exploitation of remote services (RDP, VPNs) remain prevalent.
• Attack Chain: Once inside, threat actors perform Active Directory enumeration (using tools like Bloodhound or AD Find), dump credentials (Mimikatz), move laterally (SMB/WMI), and then deploy the encryption payload.
• Impact: The encryption of files is the final stage, designed to disrupt business continuity. However, the "data breach" confirmation suggests "double extortion" tactics—data was exfiltrated prior to encryption to leverage ransom demands.
• Exploitation Status: This is a confirmed active exploitation scenario. The techniques used (mass file encryption, deletion of shadow copies) are widely available and actively being used by multiple threat actors.

Detection & Response

Given the active nature of this threat, Security Arsenal is releasing the following detection signatures to aid your SOC and IR teams. These rules focus on the precursors to encryption—disabling recovery and mass file modification—rather than just the payload itself, which changes too frequently to be a reliable primary defense.

Sigma Rules

The following Sigma rules target high-fidelity behaviors associated with ransomware operations: the deletion of Volume Shadow Copies to prevent recovery and the execution of common ransomware utilities.

---
title: Potential Ransomware Activity - VSS Shadow Copy Deletion
id: a0193206-7df6-4a9e-8236-730b8b0f4e0d
status: experimental
description: Detects attempts to delete Volume Shadow Copies via vssadmin or wmic, a common ransomware tactic to prevent file recovery.
references:
  - https://attack.mitre.org/techniques/T1490/
author: Security Arsenal
date: 2024/06/18
tags:
  - attack.impact
  - attack.t1490
logsource:
  category: process_creation
  product: windows
detection:
  selection_vssadmin:
    Image|endswith: '\vssadmin.exe'
    CommandLine|contains: 'delete shadows'
  selection_wmic:
    Image|endswith: '\wmic.exe'
    CommandLine|contains: 'shadowcopy delete'
  condition: 1 of selection_*
falsepositives:
  - System administrators managing disk space (rare)
level: critical
---
title: Ransomware - Bulk File Encryption via PowerShell
id: b1c2d3e4-5f67-89ab-cdef-0123456789ab
status: experimental
description: Detects PowerShell scripts attempting to encrypt files in bulk, often used by custom ransomware wrappers or file encryptors.
references:
  - https://attack.mitre.org/techniques/T1486/
author: Security Arsenal
date: 2024/06/18
tags:
  - attack.impact
  - attack.t1486
logsource:
  category: process_creation
  product: windows
detection:
  selection:
    Image|endswith:
      - '\powershell.exe'
      - '\pwsh.exe'
    CommandLine|contains:
      - '.Encrypt('
      - 'System.Security.Cryptography.AesManaged'
      - 'FromBase64String'
  condition: selection
falsepositives:
  - Legitimate encryption scripts by developers (should be whitelisted by path/user)
level: high

KQL (Microsoft Sentinel / Defender)

Use this KQL query to hunt for patterns of mass encryption or deletion of backup files within your environment.

DeviceProcessEvents
| where Timestamp > ago(7d)
| where FileName in~ ('vssadmin.exe', 'wbadmin.exe', 'wmic.exe')
| where ProcessCommandLine has_any ('delete', 'delete catalog', 'delete backup')
| project Timestamp, DeviceName, InitiatingProcessAccountName, FileName, ProcessCommandLine
| extend Tactics = 'Impact'

Velociraptor VQL

This Velociraptor artifact hunts for suspicious process executions that indicate ransomware preparation or deployment.

-- Hunt for ransomware precursor processes
SELECT Pid, Name, CommandLine, Exe, Username
FROM pslist()
WHERE Name =~ "vssadmin" AND CommandLine =~ "delete"
   OR Name =~ "wmic" AND CommandLine =~ "shadowcopy"
   OR Name =~ "cipher" AND CommandLine =~ "/w" 

Remediation Script (PowerShell)

Run this script on critical servers and workstations to audit the status of Volume Shadow Copies and identify if recovery mechanisms have been recently disabled.

# Audit VSS Shadow Copy Status
Write-Host "Auditing Volume Shadow Copy Status..." -ForegroundColor Cyan

$vssObjects = Get-WmiObject Win32_ShadowCopy

if ($null -eq $vssObjects) {
    Write-Host "WARNING: No Shadow Copies found on this system. Recovery may be impossible." -ForegroundColor Red
} else {
    Write-Host "Found $($vssObjects.Count) Shadow Copies." -ForegroundColor Green
    $vssObjects | Select-Object ID, VolumeName, InstallDate, OriginatingMachine | Format-Table -AutoSize
}

# Check for common ransomware extension patterns in user directories (Example check)
Write-Host "Checking for common ransomware extension patterns in C:\Users..." -ForegroundColor Cyan
$extensions = @("*.locked", "*.crypt", "*.encrypted", "*.mma")
$foundFiles = @()
foreach ($ext in $extensions) {
    $files = Get-ChildItem -Path "C:\Users" -Filter $ext -Recurse -ErrorAction SilentlyContinue
    if ($files) { $foundFiles += $files }
}

if ($foundFiles) {
    Write-Host "CRITICAL: Potential encrypted files found." -ForegroundColor Red
    $foundFiles | Select-Object FullName, LastWriteTime | Format-Table
} else {
    Write-Host "No suspicious encrypted file extensions detected." -ForegroundColor Green
}

Remediation

Based on the Starr Insurance incident and general ransomware defense hygiene, execute the following steps immediately:

1. Isolate Affected Systems: If encryption is detected, disconnect the host from the network immediately (physically disconnect if necessary) to prevent lateral movement to file shares.
2. Preserve Artifacts: Capture memory dumps and disk images of affected systems before rebooting or wiping. This is critical for identifying the initial access vector.
3. Verify Backups: Ensure that offline backups are intact and have not been encrypted or deleted. Test the restoration procedure for a subset of critical PHI data.
4. Reset Credentials: Assume that credentials have been dumped. Force a password reset for all privileged accounts and service accounts used on the affected network segment.
5. Block Command and Control (C2): If IOCs (Indicators of Compromise) become available for the specific strain targeting Starr, immediately block the associated domains and IP addresses on your perimeter firewalls and proxies.
6. HIPAA Compliance Check: Engage your Privacy Officer immediately. If PHI was confirmed to be exfiltrated, breach notification requirements under HIPAA may trigger strict timelines for reporting to HHS and affected individuals.

Related Resources

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