CVE-2025-52713

Executive Summary

CVE-2025-52713 is a Server-Side Request Forgery (SSRF) vulnerability discovered in the Post and Page Builder by BoldGrid WordPress plugin, affecting versions up to and including 1.27.8. This flaw allows an unauthenticated attacker to make arbitrary HTTP requests from the vulnerable server, potentially leading to internal network reconnaissance, port scanning, or access to cloud metadata endpoints (e.g., AWS, GCP, Azure). The vulnerability is classified as a WordPress ecosystem issue and does not involve Apache or Nginx directly.

Supply Chain & Package Security

This vulnerability resides in a WordPress plugin distributed via the official WordPress plugin repository. Users who installed the plugin via the WordPress dashboard or automated deployment tools (e.g., Composer, WP-CLI) are affected. No official patch has been released as of the latest analysis. The plugin is not distributed via NPM, PyPI, Go, or Ruby ecosystems.

CVSS Breakdown & Threat Level

• CVSS Score: 6.4 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: Low (potential internal data exposure)
• Integrity Impact: Low (potential manipulation of internal services)
• Availability Impact: None

Threat Level: Medium. While the CVSS score is moderate, the SSRF nature can be chained with other vulnerabilities (e.g., cloud metadata theft) to escalate impact.

Deep Dive & Mechanics

The vulnerability exists in the post-and-page-builder plugin's handling of user-supplied URLs during image or resource fetching. The plugin fails to validate or sanitize the target URL, allowing an attacker to specify arbitrary internal or external addresses. The server then makes HTTP requests to those addresses, enabling SSRF.

Root Cause: The plugin uses wp_remote_get() or similar WordPress HTTP API functions without proper URL validation (e.g., no blocklist for private IP ranges, no hostname allowlist).

Attack Flow:

1. Attacker identifies a vulnerable endpoint (e.g., /wp-admin/admin-ajax.php?action=boldgrid_fetch_url).
2. Attacker sends a crafted request with a target URL pointing to an internal resource (e.g., http://169.254.169.254/latest/meta-data/).
3. The server fetches the resource and returns the response to the attacker.
4. Attacker can enumerate internal services, read cloud metadata, or perform port scanning.

Vulnerable vs. Patched Code

Since no official patch is available, the following is a hypothetical fix based on common SSRF mitigation patterns.

Vulnerable Code (simplified):

function boldgrid_fetch_url() {
    $url = $_POST['url'];
    $response = wp_remote_get($url);
    echo wp_remote_retrieve_body($response);
}

Patched Code (hypothetical):

function boldgrid_fetch_url() {
    $url = $_POST['url'];
    if (!boldgrid_is_safe_url($url)) {
        wp_die('Invalid URL');
    }
    $response = wp_remote_get($url);
    echo wp_remote_retrieve_body($response);
}

function boldgrid_is_safe_url($url) {
    $parsed = parse_url($url);
    $host = $parsed['host'] ?? '';
    // Block private IP ranges
    if (filter_var($host, FILTER_VALIDATE_IP)) {
        if (!filter_var($host, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE)) {
            return false;
        }
    }
    // Allow only specific domains (example)
    $allowed = ['images.example.com', 'api.example.com'];
    if (!in_array($host, $allowed)) {
        return false;
    }
    return true;
}

Exploitation & Lab Setup

Red Team

Prerequisites:

• WordPress instance with Post and Page Builder by BoldGrid <= 1.27.8.
• Network access to the WordPress admin-ajax.php endpoint.

Exploitation Steps:

1. Identify the vulnerable AJAX action (e.g., boldgrid_fetch_url).
2. Craft a POST request to /wp-admin/admin-ajax.php with the action and a malicious URL.
3. Example using curl:

   curl -X POST http://target.com/wp-admin/admin-ajax.php \
     -d "action=boldgrid_fetch_url&url=http://169.254.169.254/latest/meta-data/"
   

4. The response will contain the cloud metadata if the server is hosted on AWS.

Advanced Exploitation:

• Use SSRF to scan internal ports (e.g., http://127.0.0.1:8080).
• Chain with other vulnerabilities (e.g., file read via file:// protocol if supported).

Blue Team

Detection:

• Monitor for unusual outbound HTTP requests from the WordPress server to internal IPs.
• Look for requests to cloud metadata endpoints (169.254.169.254, 100.100.100.200, etc.).
• Analyze web server logs for admin-ajax.php requests with suspicious url parameters.

Hunting:

• Search for boldgrid_fetch_url in access logs.
• Correlate with internal network traffic logs.

Indicators of Compromise (IOCs)

• Network IOCs:
  • Outbound HTTP requests to private IP ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16).
  • Requests to cloud metadata IPs (169.254.169.254, 100.100.100.200, 169.254.169.253).
  • Requests to localhost or 127.0.0.1.
• File IOCs:
  • Modified post-and-page-builder plugin files (if attacker uploaded a backdoor).
• Log IOCs:
  • Repeated admin-ajax.php requests with action=boldgrid_fetch_url and varying url parameters.

Detection Engineering

YARA Rule

rule CVE_2025_52713_SSRF_BoldGrid {
    meta:
        description = "Detects SSRF exploitation attempts against BoldGrid Post and Page Builder"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-52713"
    strings:
        $ajax_action = "boldgrid_fetch_url"
        $url_param = "url="
        $internal_ip = /(10\.\d{1,3}\.\d{1,3}\.\d{1,3}|172\.(1[6-9]|2[0-9]|3[01])\.\d{1,3}\.\d{1,3}|192\.168\.\d{1,3}\.\d{1,3}|127\.\d{1,3}\.\d{1,3}\.\d{1,3})/
        $metadata_ip = /169\.254\.169\.\d{1,3}/
    condition:
        $ajax_action and $url_param and ($internal_ip or $metadata_ip)
}

Sigma Rule

title: SSRF Exploitation via BoldGrid Post and Page Builder
id: 8a3f5c2e-1b4d-4f7a-9c6e-2d8b0a1e3f5c
status: experimental
description: Detects HTTP requests to internal IPs via BoldGrid plugin AJAX action
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access_log
detection:
    selection:
        cs-uri-query|contains: "action=boldgrid_fetch_url"
        cs-uri-query|contains: "url="
    filter:
        cs-uri-query|contains:
            - "url=http://10."
            - "url=http://172."
            - "url=http://192.168."
            - "url=http://127."
            - "url=http://169.254."
    condition: selection and filter
falsepositives:
    - Legitimate internal resource fetching (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-52713 SSRF Attempt - BoldGrid Plugin";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/wp-admin/admin-ajax.php"; http_uri;
    content:"action=boldgrid_fetch_url"; http_client_body;
    content:"url="; http_client_body;
    pcre:"/url=http:\/\/(10\.|172\.(1[6-9]|2[0-9]|3[01])\.|192\.168\.|127\.|169\.254\.)/Ri";
    sid:1000001;
    rev:1;
    reference:cve,2025-52713;
    priority:2;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin if not essential.
2. Implement a Web Application Firewall (WAF) rule to block requests to admin-ajax.php with action=boldgrid_fetch_url and suspicious url parameters.
3. Restrict outbound HTTP traffic from the WordPress server using network firewalls (e.g., allow only known external domains).

Long-term Fix:

• Apply the official patch once released by BoldGrid.
• If no patch is forthcoming, consider replacing the plugin with an alternative.

Workaround:

• Add the following code to the theme's functions.php to block the vulnerable action:

  add_action('wp_ajax_boldgrid_fetch_url', function() {
      wp_die('Disabled for security');
  }, 1);
  add_action('wp_ajax_nopriv_boldgrid_fetch_url', function() {
      wp_die('Disabled for security');
  }, 1);
  

Valters IT
Securing Digital Frontiers