CVE-2025-68038

Executive Summary

CVE-2025-68038 is a critical deserialization of untrusted data vulnerability in the Icegram Express Pro WordPress plugin (version < 5.9.14). This flaw allows an unauthenticated attacker to perform Object Injection by sending a crafted serialized payload to the plugin’s deserialization routine. Successful exploitation can lead to remote code execution (RCE), full site compromise, and lateral movement within the hosting environment. The vulnerability is currently unpatched with no official fix available, and no public proof-of-concept (PoC) or exploit code has been released. The EPSS score is 0.0%, indicating low exploitation activity in the wild, but the high CVSS score (7.2) and the nature of the vulnerability demand immediate attention.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository and third-party marketplaces. Organizations using Icegram Express Pro should treat this as a supply chain risk, as the plugin may be bundled with themes or other plugins. No known malicious packages have been identified, but the lack of a patch increases the risk of supply chain attacks through compromised plugin updates.

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: 7.2 (High)
• Attack Vector: Network (AV:N) – Exploitable remotely.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – No authentication needed.
• User Interaction: None (UI:N) – No user action required.
• Scope: Unchanged (S:U) – Vulnerability affects only the vulnerable component.
• Confidentiality Impact: High (C:H) – Full data access possible.
• Integrity Impact: High (I:H) – Full control over data and execution.
• Availability Impact: High (A:H) – Potential for denial of service or system crash.

Threat Level: Critical. The combination of network exploitability, no authentication, and high impact makes this a top-priority vulnerability for WordPress administrators.

Deep Dive & Mechanics

The vulnerability resides in the deserialization routine of the Icegram Express Pro plugin. The plugin likely uses PHP’s unserialize() function on user-supplied input without proper validation or sanitization. When an attacker sends a crafted serialized object (e.g., via a POST request to a vulnerable endpoint), PHP’s deserialization can instantiate arbitrary classes and trigger magic methods like __wakeup() or __destruct(). This allows the attacker to execute arbitrary code, read/write files, or escalate privileges.

Attack Flow:

1. The attacker identifies a vulnerable endpoint (e.g., /wp-admin/admin-ajax.php with a specific action).
2. The attacker crafts a serialized payload containing a gadget chain (e.g., using PHPGGC or similar tools).
3. The payload is sent to the server, where unserialize() processes it.
4. The gadget chain executes, leading to RCE or file manipulation.

Root Cause: The plugin fails to implement input validation, allowlisting of classes, or use of safer alternatives like json_decode().

Vulnerable vs. Patched Code

Since no patch is available, the following is a hypothetical comparison based on common fixes for deserialization vulnerabilities.

Vulnerable Code (hypothetical):

// vulnerable.php
$data = $_POST['data'];
$object = unserialize($data);
// process $object...

Patched Code (hypothetical):

// patched.php
$data = $_POST['data'];
// Use JSON instead of serialization
$object = json_decode($data, true);
if (json_last_error() !== JSON_ERROR_NONE) {
    die('Invalid data');
}
// Or use a whitelist approach with unserialize
$allowed_classes = ['AllowedClass1', 'AllowedClass2'];
$object = unserialize($data, ['allowed_classes' => $allowed_classes]);

Key Differences:

• The patched version avoids unserialize() entirely or restricts allowed classes.
• Input validation is added to reject malformed data.

Exploitation & Lab Setup

Red Team

Prerequisites:

• A WordPress instance with Icegram Express Pro < 5.9.14.
• PHPGGC (PHP Generic Gadget Chains) or similar tool.
• Knowledge of the vulnerable endpoint (e.g., via fuzzing or source code analysis).

Exploitation Steps:

1. Identify the vulnerable endpoint (e.g., POST /wp-admin/admin-ajax.php?action=icegram_process_data).
2. Generate a gadget chain for RCE:

   phpggc Monolog/RCE1 system 'id' | base64
   

3. Send the payload:

   curl -X POST http://target/wp-admin/admin-ajax.php \
        -d "action=icegram_process_data&data=$(phpggc Monolog/RCE1 system 'id' | base64)"
   

4. Verify execution by checking the response or out-of-band callback.

Note: No public exploit code is available; this is a hypothetical example.

Blue Team

Detection Steps:

• Monitor for unusual POST requests to admin-ajax.php with large or base64-encoded data parameters.
• Look for PHP error logs containing unserialize() errors.
• Use WAF rules to block serialized PHP objects (e.g., O:, a:, s: patterns).

Honeypot Setup:

• Deploy a decoy WordPress instance with the vulnerable plugin.
• Log all unserialize() calls and alert on suspicious payloads.

Indicators of Compromise (IOCs)

• Network IOCs:

  • POST requests to /wp-admin/admin-ajax.php with action=icegram_process_data (or similar).
  • Payloads containing base64-encoded serialized PHP objects (e.g., Tzo...).
  • Outbound connections to attacker-controlled IPs (e.g., for reverse shells).

• File IOCs:

  • Unexpected files in /wp-content/uploads/ or /tmp/ (e.g., .php webshells).
  • Modified plugin files (e.g., icegram-express-pro/*.php).

• Process IOCs:

  • PHP processes executing unusual commands (e.g., id, whoami, curl).

Detection Engineering

YARA Rule

rule CVE_2025_68038_Deserialization {
    meta:
        description = "Detects serialized PHP objects in HTTP requests targeting Icegram Express Pro"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-68038"
    strings:
        $serialized = /O:\d+:"[^"]+":\d+:\{/
        $action = "icegram_process_data"
    condition:
        $action and #serialized > 0
}

Sigma Rule

title: CVE-2025-68038 Icegram Express Pro Deserialization
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects exploitation attempts of CVE-2025-68038 via serialized PHP objects
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        c-uri: '/wp-admin/admin-ajax.php'
        cs-uri-query: 'action=icegram_process_data'
        cs-body: 'O:*'
    condition: selection
falsepositives:
    - Legitimate plugin functionality (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-68038 Icegram Express Pro Deserialization Attempt"; flow:to_server; content:"POST"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"action=icegram_process_data"; http_client_body; content:"O:"; within:100; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is released.
2. Apply a virtual patch using a WAF (e.g., ModSecurity) to block serialized PHP objects:

   SecRule REQUEST_BODY "O:\d+:" "id:1000001,phase:2,deny,status:403,msg:'CVE-2025-68038 blocked'"
   

3. Monitor logs for exploitation attempts.

Long-term Fix:

• Replace unserialize() with json_decode() or implement class allowlisting.
• Update to version 5.9.14 or later once available.

Workarounds:

• Use a PHP-based patch (e.g., override the vulnerable function via a custom plugin).
• Restrict access to admin-ajax.php via .htaccess:

  <Files "admin-ajax.php">
      Require all denied
  </Files>
  

Valters IT
Cyber Threat Intelligence & DevSecOps