SOC Guide: Protecting Healthcare Java Apps with YARA, KQL & SOAR

1. Introduction

Audience: Healthcare IT security teams managing credential-based Java applications (EHRs, patient portals) with:

• Large # of users
• Possible issues with 2FA or FIDO2 implementations (bound to username/password only controls only)
• Browser-based interfaces

Scope: Covers threat detection (YARA, KQL), incident response playbooks, and SOAR automation for:

• Credential stuffing
• Ransomware
• EHR data exfiltration
• Framework exploits (Log4j, Spring4Shell)

2. Critical Threat Detection

A. Key Log Sources to Monitor

<table style="border: 1px solid lightgrey; border-collapse: collapse; width: 100%;">
    <thead>
        <tr style="border: 1px solid lightgrey;">
            <th style="border: 1px solid lightgrey; padding: 8px;">Log Type</th>
            <th style="border: 1px solid lightgrey; padding: 8px;">Critical Alerts</th>
            <th style="border: 1px solid lightgrey; padding: 8px;">Sample KQL</th>
        </tr>
    </thead>
    <tbody>
        <tr style="border: 1px solid lightgrey;">
            <td style="border: 1px solid lightgrey; padding: 8px;">Authentication</td>
            <td style="border: 1px solid lightgrey; padding: 8px;">Brute force, impossible travel</td>
            <td style="border: 1px solid lightgrey; padding: 8px;"><code>SecurityEvent | where EventID == 4625</code></td>
        </tr>
        <tr style="border: 1px solid lightgrey;">
            <td style="border: 1px solid lightgrey; padding: 8px;">EHR Access</td>
            <td style="border: 1px solid lightgrey; padding: 8px;">Mass record downloads</td>
            <td style="border: 1px solid lightgrey; padding: 8px;"><code>AuditLogs | where Operation == "ReadPatientRecord"</code></td>
        </tr>
        <tr style="border: 1px solid lightgrey;">
            <td style="border: 1px solid lightgrey; padding: 8px;">Network</td>
            <td style="border: 1px solid lightgrey; padding: 8px;">Unencrypted PHI transfers</td>
            <td style="border: 1px solid lightgrey; padding: 8px;"><code>NetworkLogs | where Protocol == "HTTP" and isempty(SSLVersion)</code></td>
        </tr>
    </tbody>
</table>

B. YARA Rules for Healthcare Threats

Detect Ransomware Payloads

rule Java_Ransomware {  
  strings: $encrypt = "Cipher.getInstance(\"AES\")", $note = "YOUR_FILES_ARE_ENCRYPTED"  
  condition: $encrypt and $note  
}  

EPIC/Cerner API Scraping

rule EHR_API_Scraper {  
  strings: $epic_api = "/api/FHIR/R4/Patient", $mass_query = "?_count=1000"  
  condition: $epic_api and $mass_query  
}  

3. SOAR Playbooks for Automated Response

Assumes integration with Microsoft Sentinel, Splunk SOAR, or Demisto.

Playbook 1: Brute Force Attack Response

Trigger: >5 failed logins/minute from a single IP.
Automated Actions:

1. Block IP in firewall (via API call to Palo Alto/Cisco).
2. Disable compromised account (Active Directory API).
3. Alert SOC via Teams/Slack with attacker IP and username.
4. Enforce 2FA for the affected user (Okta/Azure AD API).

# Pseudocode for Splunk SOAR  
def handle_brute_force(event):  
    ip = event.get('src_ip')  
    user = event.get('account')  
    block_ip(ip)  # Firewall API call  
    disable_user(user)  # AD API call  
    send_alert(f"Brute force attack blocked: {user} from {ip}")  

Playbook 2: Ransomware Encryption Detected

Trigger: Mass file renames to .encrypted or .locky.
Automated Actions:

1. Isolate host (EDR API like CrowdStrike).
2. Kill malicious process (e.g., java.exe with suspicious args).
3. Restore files from backup (Storage Area Network API).
4. Trigger IR workflow (assign to SOC Tier 2).

# Pseudocode for Demisto  
def handle_ransomware(file_event):  
    host = file_event.get('hostname')  
    isolate_host(host)  # EDR API  
    kill_process(file_event.get('process_id'))  
    restore_files(file_event.get('file_paths'))  

Playbook 3: EHR Data Exfiltration

Trigger: 100+ patient records downloaded by a single user in 1 hour.
Automated Actions:

1. Revoke user sessions (Okta/Azure AD API).
2. Quarantine exported files (DLP tool API).
3. Freeze user account and alert legal/compliance teams.

# Pseudocode for Microsoft Sentinel Logic App  
def handle_data_exfil(user):  
    revoke_sessions(user)  
    quarantine_files(f"User {user} exported PHI")  
    notify_legal_team(user)  

4. Compliance & Reporting

HIPAA/GDPR Automated Reports

• Weekly Access Audits:

  AuditLogs | summarize RecordsAccessed=count() by UserId, PatientID  
  

• Breach Notification Workflow: Auto-generate reports for regulators when PHI is exfiltrated.

5. MITRE ATT&CK Mapping

6. Deployment Checklist

A. For YARA Rules

• Deploy on EDR (CrowdStrike/SentinelOne) and CI/CD pipelines.
• Scan all .jar, .jsp, and .class files.

B. For KQL & SOAR

1. Import queries into Microsoft Sentinel/Splunk.
2. Test playbooks in staging with mock attacks.
3. Set thresholds: E.g., >5 failed logins = critical alert.

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