CVE-2025-1913

Executive Summary

CVE-2025-1913 is a critical PHP Object Injection vulnerability discovered in the WordPress plugin Product Import Export for WooCommerce – Import Export Product CSV Suite by Webtoffee. The flaw exists in all versions up to and including 2.5.0, where the plugin deserializes untrusted input from the form_data parameter without proper sanitization. This allows authenticated attackers with Administrator-level access to inject arbitrary PHP objects. While no known POP (Property Oriented Programming) chain exists within the vulnerable plugin itself, the presence of any other plugin or theme containing a POP chain on the same WordPress site can lead to severe consequences, including arbitrary file deletion, sensitive data exfiltration, or remote code execution. The vulnerability is classified under CWE-502 (Deserialization of Untrusted Data) and carries a CVSS score of 7.2 (High). Given the high privileges required (Administrator), the attack surface is limited but poses a significant risk in multi-tenant or shared hosting environments where a compromised admin account could be leveraged.

Supply Chain & Package Security

This vulnerability is specific to the WordPress plugin ecosystem. The plugin is distributed via the official WordPress Plugin Directory and third-party marketplaces. Users are advised to verify the integrity of their plugin files and ensure they are sourced from trusted repositories. No known supply chain compromise has been reported for this specific CVE, but the risk of dependency-based attacks (e.g., via a POP chain in another plugin) remains.

CVSS Breakdown & Threat Level

• CVSS Score: 7.2 (High)
• 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.
• Attack Complexity (AC): Low – No special conditions are required.
• Privileges Required (PR): High – Administrator-level access is needed.
• User Interaction (UI): None – No user action is required.
• Scope (S): Unchanged – The vulnerable component and the impacted component are the same.
• Confidentiality (C): High – Potential for sensitive data exposure.
• Integrity (I): High – Potential for arbitrary file modification or code execution.
• Availability (A): High – Potential for denial of service or system compromise.

Threat Level: High. Although the EPSS score is 0.0% (indicating low exploitation likelihood in the wild), the potential impact is severe due to the possibility of chaining with other vulnerabilities.

Deep Dive & Mechanics

The vulnerability resides in the form_data parameter handling within the plugin's import/export functionality. The plugin uses PHP's unserialize() function on user-supplied data without proper validation. When an authenticated administrator submits a crafted request (e.g., via the WooCommerce import/export interface), the plugin deserializes the form_data parameter, allowing the injection of arbitrary PHP objects.

Technical Flow:

1. The plugin receives a POST request containing the form_data parameter.
2. The value of form_data is passed directly to unserialize().
3. If a POP chain exists in another installed plugin or theme, the injected object triggers gadget methods (e.g., __wakeup(), __destruct(), __toString()).
4. This can lead to arbitrary code execution, file deletion, or data exfiltration.

Key Code Snippet (Vulnerable):

$form_data = isset($_POST['form_data']) ? $_POST['form_data'] : '';
$data = unserialize(stripslashes($form_data));

Why it's dangerous: The unserialize() function in PHP is inherently unsafe when used with untrusted input. Even without a POP chain, an attacker can cause denial of service or memory corruption. With a POP chain, the impact escalates to full system compromise.

Vulnerable vs. Patched Code

Vulnerable Code (version <= 2.5.0):

// In some handler file
$form_data = isset($_POST['form_data']) ? $_POST['form_data'] : '';
$data = unserialize(stripslashes($form_data));

Patched Code (hypothetical, based on best practices):

// Use JSON instead of serialization
$form_data = isset($_POST['form_data']) ? $_POST['form_data'] : '';
$data = json_decode(stripslashes($form_data), true);
if (json_last_error() !== JSON_ERROR_NONE) {
    // Handle error
    wp_die('Invalid form data');
}

Explanation: The patched version replaces unserialize() with json_decode(), which is safe from object injection. Additionally, input validation and sanitization should be applied to ensure the data conforms to expected types.

Exploitation & Lab Setup

Red Team (Attack Simulation)

Prerequisites:

• A WordPress site with the vulnerable plugin (<= 2.5.0) installed.
• Administrator credentials.
• A POP chain gadget in another installed plugin or theme (e.g., from a known vulnerable plugin like wp-gdpr-compliance).

Exploit Steps:

1. Identify the vulnerable endpoint (e.g., /wp-admin/admin-ajax.php?action=import_export_handler).
2. Craft a serialized payload containing a malicious object that triggers a POP chain.
3. Send a POST request with the payload in the form_data parameter.

Example Payload (using a hypothetical POP chain):

// Assume a POP chain exists in another plugin with class 'EvilClass' having __destruct() that executes code.
$payload = serialize(new EvilClass());
// URL encode and send
$post_data = array(
    'action' => 'import_export_handler',
    'form_data' => urlencode($payload)
);
$ch = curl_init('http://target.com/wp-admin/admin-ajax.php');
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $post_data);
curl_setopt($ch, CURLOPT_COOKIE, 'wordpress_logged_in_...'); // Admin cookie
curl_exec($ch);

Note: Since no public exploit exists, this is a conceptual demonstration. The actual POP chain must be identified from other installed components.

Blue Team (Defense & Detection)

Detection Strategy:

• Monitor for unusual unserialize() calls in PHP error logs.
• Look for POST requests to /wp-admin/admin-ajax.php with large or suspicious form_data parameters.
• Use WAF rules to block serialized PHP objects (e.g., patterns like O:\d+:").

Honeypot Setup:

• Deploy a decoy WordPress instance with the vulnerable plugin and a fake POP chain plugin.
• Log all form_data submissions for analysis.

Indicators of Compromise (IOCs)

• File System:
  • Unexpected files in /wp-content/uploads/ or /tmp/.
  • Modified .php files in plugin directories.
• Network:
  • Outbound connections to unknown IPs from the web server.
  • POST requests to /wp-admin/admin-ajax.php with form_data containing serialized PHP objects (pattern: O:\d+:").
• Logs:
  • PHP error logs showing unserialize() errors or unexpected class loading.
  • WordPress debug logs with __PHP_Incomplete_Class entries.
• Processes:
  • Unusual PHP processes running with high CPU or memory.

Detection Engineering

YARA Rule

rule CVE_2025_1913_PHP_Object_Injection {
    meta:
        description = "Detects PHP serialized objects in form_data parameter for CVE-2025-1913"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-1913"
    strings:
        $serialized = /O:\d+:"/
        $form_data = /form_data=/
    condition:
        $serialized and $form_data
}

Sigma Rule

title: CVE-2025-1913 - PHP Object Injection via form_data
id: 8a2b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects attempts to exploit PHP Object Injection in Product Import Export for WooCommerce plugin
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access_combined
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'action=import_export_handler'
        cs-uri-query|contains: 'form_data='
        cs-uri-query|re: 'O:\d+:"'
    condition: selection
falsepositives:
    - Legitimate use of serialized data (unlikely)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-1913 - PHP Object Injection Attempt"; flow:to_server,established; content:"POST"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"action=import_export_handler"; http_client_body; content:"form_data="; http_client_body; pcre:"/O:\d+:\"/"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade the plugin to a patched version (if available) or remove it until a patch is released.
2. Restrict Administrator access to only trusted users.
3. Disable unused plugins and themes to reduce the risk of POP chains.
4. Implement a Web Application Firewall (WAF) rule to block serialized PHP objects in POST data.

Long-term Mitigations:

• Code Audit: Review all unserialize() calls in custom code and replace with json_decode().
• Input Validation: Use whitelisting and type checking for all user-supplied data.
• Least Privilege: Ensure WordPress admin accounts have minimal necessary permissions.
• Monitoring: Deploy the above detection rules and monitor logs for suspicious activity.

Patch Details: As of this report, no official patch has been released by Webtoffee. Users should monitor the plugin's changelog and apply updates as soon as they become available.

Valters IT
Securing Digital Frontiers