CVE-2025-60229

Executive Summary

CVE-2025-60229 is a critical deserialization vulnerability in the Lagom WordPress theme by Themeton. The flaw allows an unauthenticated attacker to perform Object Injection via deserialization of untrusted data. This can lead to remote code execution (RCE), full site compromise, and data exfiltration. The CVSS score is 9.8 (Critical), and no patch is currently available. The vulnerability affects all versions of Lagom from n/a through 2.0.

Supply Chain & Package Security

This vulnerability resides in a WordPress theme distributed via the official WordPress theme repository and third-party marketplaces. Users who installed Lagom from any source are at risk. Since the vendor has not provided a patch, the supply chain risk is elevated. Organizations should treat this as a zero-day and immediately isolate any sites running the affected theme.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
• Base Score: 9.8 (Critical)
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: High
• Availability Impact: High

The vulnerability is trivially exploitable by any remote attacker without authentication, making it a top priority for remediation.

Deep Dive & Mechanics

The vulnerability exists in the Lagom theme's handling of serialized PHP objects. The theme likely uses unserialize() on user-supplied input without proper validation or sanitization. An attacker can craft a malicious serialized object that, when deserialized, triggers arbitrary PHP object instantiation and method execution. This can lead to:

• Remote code execution via gadget chains (e.g., using common WordPress or PHP classes).
• Database manipulation.
• Privilege escalation.
• Full site takeover.

The lack of a patch means that any site using Lagom <= 2.0 is vulnerable until the theme is removed or a third-party workaround is applied.

Vulnerable vs. Patched Code

Since no patch exists, the vulnerable code is presumed to be in the theme's core files, likely in a function that processes user input (e.g., $_POST, $_GET, or cookie data) with unserialize().

Vulnerable Code (Hypothetical):

$data = unserialize($_POST['theme_data']);

Patched Code (Recommended):

$data = json_decode(wp_unslash($_POST['theme_data']), true);

The patched version would replace unserialize() with a safe alternative like json_decode() and ensure input is properly sanitized.

Exploitation & Lab Setup

Red Team

1. Setup: Deploy a WordPress instance with Lagom theme version 2.0.
2. Craft Payload: Use PHPGGC or similar tool to generate a gadget chain for RCE.

   phpggc WordPress/RCE1 system 'id' > payload.txt
   

3. Send Exploit: Submit the serialized payload to the vulnerable endpoint.

   curl -X POST http://target/wp-content/themes/lagom/vulnerable.php \
     -d "theme_data=$(cat payload.txt)"
   

4. Verify: Check for command output or a reverse shell.

Blue Team

1. Detection: Monitor for unusual POST requests to theme files.
2. Honeypot: Deploy a decoy WordPress site with Lagom to capture exploit attempts.
3. WAF Rule: Block requests containing serialized PHP objects.

   if ($request_body ~* "O:[0-9]+:") {
       return 403;
   }
   

Indicators of Compromise (IOCs)

• Network: POST requests to /wp-content/themes/lagom/*.php with serialized PHP objects (e.g., O:14:"WP_Post":1:{...}).
• File: Unexpected files in /wp-content/uploads/ or /tmp/ (e.g., shell.php).
• Process: php processes executing unusual commands.
• Log: PHP error logs showing unserialize() errors or __destruct calls.

Detection Engineering

YARA Rule

rule CVE_2025_60229_Lagom_Deserialization {
    meta:
        description = "Detects serialized PHP objects in HTTP requests targeting Lagom theme"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-60229"
    strings:
        $serialized = /O:[0-9]+:"/
        $lagom_path = /wp-content\/themes\/lagom/
    condition:
        $serialized and $lagom_path
}

Sigma Rule

title: CVE-2025-60229 Lagom Deserialization Attempt
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects HTTP POST requests containing serialized PHP objects to Lagom theme files
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: '/wp-content/themes/lagom/'
        cs-body|contains: 'O:'
    condition: selection
falsepositives:
    - Legitimate use of serialized data (rare)
level: critical

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-60229 Lagom Deserialization Attempt"; flow:to_server,established; content:"POST"; http_method; content:"/wp-content/themes/lagom/"; http_uri; content:"O:"; http_client_body; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate: Remove or disable the Lagom theme on all WordPress sites.
2. Alternative: Switch to a different, actively maintained theme.
3. WAF: Deploy a Web Application Firewall rule to block serialized PHP objects.
4. Monitoring: Enable logging and alerting for the IOCs listed above.
5. Vendor Contact: Pressure Themeton to release a security patch.

Valters IT
Securing Digital Frontiers