CVE-2024-6648

Executive Summary

CVE-2024-6648 is a critical Absolute Path Traversal vulnerability affecting the AP Page Builder WordPress plugin in versions prior to 4.0.0. An unauthenticated remote attacker can manipulate the product_item_path parameter within the plugin's config JSON file, enabling arbitrary file read on the server. This allows the attacker to exfiltrate sensitive data such as wp-config.php, database credentials, and other system files. The vulnerability has a CVSS base score of 7.5 (High) due to its network exploitability and low attack complexity. No public proof-of-concept (PoC) or exploit code has been released at this time, but the risk remains significant for unpatched installations.

Supply Chain & Package Security

This vulnerability resides in a WordPress plugin ecosystem. The AP Page Builder plugin is distributed via the official WordPress plugin repository and third-party marketplaces. Users are advised to verify the integrity of their plugin files and ensure they are sourced from trusted channels. The plugin's update mechanism should be used to apply the patch immediately.

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 only affected component.
• Confidentiality (C): High (H) – Complete file read capability.
• Integrity (I): None (N) – No file modification.
• Availability (A): None (N) – No denial of service.

CVSS Score: 7.5 (High)
Threat Level: High – Immediate patching recommended.

Deep Dive & Mechanics

The vulnerability exists in the AP Page Builder plugin's handling of the product_item_path configuration parameter. The plugin reads a JSON configuration file (config.json) that contains various settings, including product_item_path. This parameter is used to specify the base path for product item templates. Due to insufficient input validation and sanitization, an attacker can supply a path traversal sequence (e.g., ../../../etc/passwd) as the value of product_item_path. The plugin then uses this unsanitized path in file read operations, allowing the attacker to read arbitrary files on the server.

The attack flow:

1. The attacker sends a crafted HTTP request to the WordPress site, targeting the plugin's AJAX endpoint or configuration update mechanism.
2. The request includes a modified product_item_path parameter containing path traversal sequences.
3. The plugin writes this malicious value to the config.json file.
4. When the plugin later reads a file using the product_item_path, it resolves to an arbitrary system file.
5. The file contents are returned to the attacker in the HTTP response.

This vulnerability is particularly dangerous because it requires no authentication and can be exploited remotely. The attacker can read sensitive files such as /etc/passwd, /etc/shadow, database configuration files, and WordPress secrets.

Vulnerable vs. Patched Code

Vulnerable Code (versions < 4.0.0):

// In vulnerable versions, the product_item_path is not sanitized
$config = json_decode(file_get_contents('config.json'), true);
$path = $config['product_item_path'];
$content = file_get_contents($path); // No validation
echo $content;

Patched Code (version 4.0.0):

// In patched version, path is validated and restricted
$config = json_decode(file_get_contents('config.json'), true);
$path = $config['product_item_path'];
// Ensure path is within allowed directory
$allowed_dir = WP_CONTENT_DIR . '/uploads/ap-page-builder/';
$real_path = realpath($path);
if (strpos($real_path, $allowed_dir) === 0) {
    $content = file_get_contents($real_path);
    echo $content;
} else {
    // Log and deny access
    error_log('Path traversal attempt detected: ' . $path);
    wp_die('Invalid path.');
}

Exploitation & Lab Setup

Red Team (Attack Simulation)

Prerequisites:

• A WordPress installation with AP Page Builder plugin version < 4.0.0.
• Network access to the WordPress admin or AJAX endpoints.

Exploitation Steps:

1. Identify the vulnerable endpoint (e.g., /wp-admin/admin-ajax.php with action ap_page_builder_update_config).
2. Craft a POST request with the malicious payload:

POST /wp-admin/admin-ajax.php HTTP/1.1
Host: target-wordpress-site.com
Content-Type: application/x-www-form-urlencoded

action=ap_page_builder_update_config&product_item_path=../../../etc/passwd

3. The server responds with the contents of /etc/passwd.

Alternative Exploit using cURL:

curl -X POST https://target-wordpress-site.com/wp-admin/admin-ajax.php \
  -d "action=ap_page_builder_update_config&product_item_path=../../../etc/passwd"

Blue Team (Defense & Detection)

Detection Steps:

1. Monitor for unusual POST requests to admin-ajax.php with the action=ap_page_builder_update_config parameter.
2. Look for path traversal patterns in the product_item_path parameter (e.g., ../, ..\\, %2e%2e%2f).
3. Check for unexpected file read operations from the web server process.

Hunting Query (Splunk):

index=web sourcetype=access_combined
| search uri="/wp-admin/admin-ajax.php" AND form_data=*product_item_path*
| rex field=form_data "product_item_path=(?<path>[^&]+)"
| search path IN (*../*, *..\\*, *%2e%2e*)
| table _time, src_ip, uri, path, status

Indicators of Compromise (IOCs)

• Network IOCs:

  • POST requests to /wp-admin/admin-ajax.php with action=ap_page_builder_update_config and product_item_path containing path traversal sequences.
  • Outbound connections from the web server to unknown IPs (if exfiltrating data).

• File System IOCs:

  • Modified config.json file in the plugin directory containing path traversal strings.
  • Unexpected file access logs in /var/log/apache2/access.log or /var/log/nginx/access.log.

• Log IOCs:

  • PHP error logs showing file_get_contents failures for paths outside the allowed directory.
  • WordPress debug logs with path traversal attempts.

Detection Engineering

YARA Rule

rule CVE_2024_6648_Path_Traversal {
    meta:
        description = "Detects path traversal attempts targeting AP Page Builder plugin"
        author = "Valters IT"
        date = "2024-01-01"
        reference = "CVE-2024-6648"
    strings:
        $traversal1 = "../"
        $traversal2 = "..\\"
        $traversal3 = "%2e%2e%2f"
        $traversal4 = "%2e%2e%5c"
        $param = "product_item_path"
    condition:
        any of ($traversal*) and $param
}

Sigma Rule

title: CVE-2024-6648 AP Page Builder Path Traversal
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects path traversal attempts in AP Page Builder plugin
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-uri-query|contains: 
            - "action=ap_page_builder_update_config"
            - "product_item_path="
        cs-uri-query|contains|all:
            - "../"
            - "..\\"
            - "%2e%2e%2f"
    condition: selection
falsepositives:
    - Legitimate use of relative paths (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-6648 AP Page Builder Path Traversal Attempt"; flow:to_server,established; content:"POST"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"action=ap_page_builder_update_config"; http_client_body; content:"product_item_path="; http_client_body; pcre:"/product_item_path=[^&]*(\.\.\/|\.\.\\|%2e%2e%2f|%2e%2e%5c)/i"; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Update the plugin: Upgrade AP Page Builder to version 4.0.0 or later immediately.
2. Verify integrity: After updating, verify that the config.json file does not contain malicious path entries.
3. Restrict file permissions: Ensure the web server user has minimal read permissions on sensitive system files.

Long-term Mitigations:

1. Web Application Firewall (WAF): Deploy rules to block path traversal patterns in POST parameters.
2. Input Validation: Implement strict input validation for all configuration parameters.
3. Least Privilege: Run the web server with the least privileges necessary.
4. Monitoring: Enable detailed logging and monitor for path traversal attempts.

Workaround (if patching is not immediately possible):

• Disable the AP Page Builder plugin until the update can be applied.
• Use a WAF to block requests containing product_item_path with path traversal sequences.

Valters IT
DevSecOps & Cyber Threat Intelligence