CVE-2025-56556

Executive Summary

CVE-2025-56556 is a privilege escalation vulnerability in Subrion CMS version 4.2.1. The flaw resides in the built-in "Run SQL Query" feature under the SQL Tool admin panel. Authenticated administrators or moderators with access to this tool can execute arbitrary SQL queries, effectively gaining escalated privileges within the context of the SQL query tool itself. This allows an attacker to bypass intended restrictions and perform actions beyond their assigned role, potentially leading to full database compromise.

The vulnerability has a CVSS score of 0.0 (placeholder) but based on the vector, it is rated High severity. No public exploit code or proof-of-concept is currently available. The vendor has not released a patch, and the status remains unknown.

Supply Chain & Package Security

This vulnerability is not related to a package manager (NPM, PyPI, Go, Ruby). It is a direct issue within the Subrion CMS application codebase.

CVSS Breakdown & Threat Level

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

• Attack Vector (AV): Network – The vulnerability can be exploited remotely over the network.
• Attack Complexity (AC): Low – No special conditions are required for exploitation.
• Privileges Required (PR): High – An attacker must have valid administrator or moderator credentials.
• User Interaction (UI): None – No user interaction is required.
• Scope (S): Unchanged – The vulnerable component and the impacted component are the same.
• Confidentiality (C): High – Full database read access is possible.
• Integrity (I): High – Full database write/modify access is possible.
• Availability (A): High – Database operations can disrupt availability.

Threat Level: High. While authentication is required, the impact is severe as it allows complete control over the database.

Deep Dive & Mechanics

The vulnerability exists in the SQL Tool admin panel, specifically in the runSqlQuery functionality. The application fails to properly validate or restrict the SQL queries that an authenticated user can execute. While the feature is intended for database administration, it does not enforce role-based restrictions on the types of queries allowed.

Root Cause: The application does not implement a whitelist of allowed SQL commands or sanitize the input to prevent dangerous operations (e.g., DROP, ALTER, INSERT into system tables). An authenticated moderator with access to the SQL Tool can execute arbitrary SQL statements, effectively gaining the same privileges as a database administrator.

Attack Flow:

1. Attacker logs in as an administrator or moderator with access to the SQL Tool.
2. Attacker navigates to the SQL Tool panel (e.g., /panel/database/sql/).
3. Attacker submits a malicious SQL query, such as:

   INSERT INTO `core_users` (`username`, `password`, `usergroup`) VALUES ('backdoor', 'hash', 1);
   

4. The query is executed without restriction, creating a new admin user or modifying existing data.
5. Attacker can now perform any database operation, including reading sensitive data, modifying content, or dropping tables.

Vulnerable vs. Patched Code

Vulnerable Code (Subrion CMS 4.2.1): The SQL query execution function likely looks like this (simplified):

// vulnerable.php
public function runSqlQuery($query) {
    $db = $this->getDatabase();
    $result = $db->query($query);
    return $result;
}

No input validation or restriction is applied.

Patched Code (Hypothetical): A patched version would implement a whitelist of allowed SQL commands and restrict dangerous operations:

// patched.php
public function runSqlQuery($query) {
    $allowed_commands = ['SELECT', 'SHOW', 'DESCRIBE', 'EXPLAIN'];
    $command = strtoupper(explode(' ', trim($query))[0]);
    if (!in_array($command, $allowed_commands)) {
        throw new Exception('SQL command not allowed.');
    }
    $db = $this->getDatabase();
    $result = $db->query($query);
    return $result;
}

Exploitation & Lab Setup

Red Team

Prerequisites:

• Valid admin or moderator credentials with access to the SQL Tool.
• Network access to the Subrion CMS admin panel.

Exploitation Steps:

1. Log in to the admin panel.
2. Navigate to the SQL Tool (e.g., /panel/database/sql/).
3. Execute a malicious query to create a backdoor admin user:

   INSERT INTO `core_users` (`username`, `password`, `usergroup`) VALUES ('attacker', MD5('password123'), 1);
   

4. Log out and log in with the new credentials (attacker:password123).
5. Now you have full admin access.

Alternative Payloads:

• Read sensitive data:

  SELECT * FROM `core_config`;
  

• Modify site content:

  UPDATE `core_pages` SET `content` = 'Hacked' WHERE `id` = 1;
  

Blue Team

Detection:

• Monitor SQL Tool access logs for unusual queries.
• Alert on queries containing INSERT, UPDATE, DELETE, DROP, ALTER, CREATE, TRUNCATE.
• Monitor for creation of new admin users or changes to user groups.

Hunting:

• Search for SQL queries executed via the SQL Tool that are not SELECT or SHOW.
• Look for multiple failed login attempts followed by successful SQL Tool usage.

Lab Setup:

1. Install Subrion CMS 4.2.1 on a local server (e.g., using Docker).
2. Create an admin account.
3. Enable detailed logging for the SQL Tool.
4. Execute the exploit and observe logs.

Indicators of Compromise (IOCs)

Network IOCs:

• HTTP POST requests to /panel/database/sql/ with SQL keywords in the body.
• Unusual SQL commands in POST data (e.g., INSERT, DROP, ALTER).

Host IOCs:

• New entries in core_users table with unexpected usernames.
• Modified core_config or core_pages table entries.
• Database error logs showing failed SQL execution attempts.

File IOCs:

• Modified PHP files in the admin directory (if attacker uploads a webshell).
• New files in the uploads directory (if attacker uses SQL to write files).

Detection Engineering

YARA Rule

rule Detect_Subrion_SQL_Tool_Exploit {
    meta:
        description = "Detects SQL injection attempts via Subrion CMS SQL Tool"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-56556"
    strings:
        $sql_tool_path = "/panel/database/sql/"
        $dangerous_sql = /(INSERT|UPDATE|DELETE|DROP|ALTER|CREATE|TRUNCATE|EXEC|EXECUTE)\s/i
    condition:
        $sql_tool_path and $dangerous_sql
}

Sigma Rule

title: Subrion CMS SQL Tool Privilege Escalation
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects dangerous SQL queries executed via Subrion CMS SQL Tool
author: Valters IT
date: 2025/04/10
logsource:
    category: webserver
    product: apache
    service: access_combined
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/panel/database/sql/'
        cs-uri-query|contains: 
            - 'INSERT'
            - 'UPDATE'
            - 'DELETE'
            - 'DROP'
            - 'ALTER'
            - 'CREATE'
            - 'TRUNCATE'
    condition: selection
falsepositives:
    - Legitimate database administration by authorized users
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-56556 Subrion CMS SQL Tool Privilege Escalation";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/panel/database/sql/"; http_uri;
    content:"INSERT" or content:"UPDATE" or content:"DELETE" or content:"DROP" or content:"ALTER" or content:"CREATE" or content:"TRUNCATE";
    classtype:attempted-admin;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Restrict Access: Limit the SQL Tool feature to only super-administrators. Remove moderator access.
2. Disable SQL Tool: If not required, disable the SQL Tool entirely via configuration.
3. Web Application Firewall (WAF): Deploy WAF rules to block dangerous SQL keywords in POST requests to /panel/database/sql/.

Long-term Fix:

• Apply input validation and whitelist allowed SQL commands (SELECT, SHOW, DESCRIBE, EXPLAIN only).
• Implement role-based access control (RBAC) to restrict SQL Tool usage.
• Monitor vendor for official patch; if none, consider custom patching or migration.

Workaround:

• Remove the SQL Tool plugin or module if it is optional.
• Use database-level permissions to restrict the CMS database user to read-only operations.

Valters IT
Securing Digital Frontiers