CVE-2025-68030

Executive Summary

CVE-2025-68030 is a Server-Side Request Forgery (SSRF) vulnerability discovered in the WordPress plugin Frontis Blocks by WP Messiah. The flaw affects all versions up to and including 1.1.5. An unauthenticated attacker can exploit this vulnerability to make the server send crafted HTTP requests to internal or external systems, potentially leading to information disclosure, internal network scanning, or further exploitation of internal services. The vulnerability resides in the plugin's block rendering functionality, which fails to properly validate user-supplied URLs before making server-side requests. No public proof-of-concept (PoC) exploit or patch details are currently available.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. Users who have installed Frontis Blocks from the WordPress admin dashboard or via direct download are at risk. The plugin is not distributed via NPM, PyPI, Go, or Ruby ecosystems. The lack of a patch from the vendor increases supply chain risk, as users must rely on manual mitigation or removal of the plugin.

CVSS Breakdown & Threat Level

• CVSS Score: 7.2 (High)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: High (C:H)
• Integrity Impact: Low (I:L)
• Availability Impact: None (A:N)

The high confidentiality impact reflects the potential for an attacker to read internal resources (e.g., cloud metadata, internal web apps). The low integrity impact indicates limited ability to modify data, while no availability impact is expected.

Deep Dive & Mechanics

The SSRF vulnerability in Frontis Blocks arises from improper sanitization of the url parameter used in the plugin's block rendering. When a user creates a block that fetches external content (e.g., an image or embed), the plugin makes a server-side HTTP request to the provided URL. The plugin fails to validate that the URL points to an allowed external domain, allowing an attacker to specify internal IP addresses (e.g., http://169.254.169.254/ for cloud metadata) or internal services (e.g., http://localhost:9200/ for Elasticsearch).

The vulnerable code likely uses a function like wp_remote_get() or file_get_contents() without a proper allowlist or blocklist. An attacker can craft a malicious request to the WordPress site, triggering the plugin to make a request to an internal resource. The response is then reflected back to the attacker, enabling data exfiltration.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code is presumed to be in the plugin's main block handler. A typical vulnerable pattern might look like:

// Vulnerable code (conceptual)
function frontis_fetch_block_content($url) {
    $response = wp_remote_get($url); // No validation
    return wp_remote_retrieve_body($response);
}

A patched version would include URL validation:

// Patched code (conceptual)
function frontis_fetch_block_content($url) {
    $allowed_hosts = array('example.com', 'cdn.example.com');
    $parsed_url = parse_url($url);
    if (!in_array($parsed_url['host'], $allowed_hosts)) {
        return 'Blocked: URL not allowed';
    }
    $response = wp_remote_get($url);
    return wp_remote_retrieve_body($response);
}

Exploitation & Lab Setup

Red Team

To exploit this vulnerability in a lab environment:

1. Set up a WordPress instance with Frontis Blocks version 1.1.5 installed and activated.
2. Create a malicious block that triggers an SSRF to an internal service. For example, use a custom block with a URL parameter pointing to http://169.254.169.254/latest/meta-data/ (AWS metadata endpoint).
3. Send a crafted HTTP request to the WordPress site, e.g., via a POST to the block rendering endpoint:

   POST /wp-json/frontis-blocks/v1/fetch HTTP/1.1
   Host: target-wordpress-site.com
   Content-Type: application/json
   
   {"url": "http://169.254.169.254/latest/meta-data/"}
   

4. Observe the response containing the cloud metadata.

Blue Team

To detect exploitation attempts:

• Monitor outbound HTTP requests from the WordPress server to internal IP ranges (e.g., 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16, 169.254.0.0/16).
• Look for requests to cloud metadata endpoints (e.g., 169.254.169.254).
• Analyze web server logs for unusual URL parameters containing internal IP addresses or hostnames.

Indicators of Compromise (IOCs)

• Network IOCs:

  • Outbound HTTP requests to internal IP addresses (e.g., 10.0.0.1, 192.168.1.1, 169.254.169.254)
  • Requests to cloud metadata endpoints (e.g., http://169.254.169.254/latest/meta-data/)
  • Unusual User-Agent strings in outbound requests (e.g., WordPress/6.x; Frontis Blocks)

• File IOCs:

  • Presence of the plugin directory: /wp-content/plugins/frontis-blocks/
  • Modified or suspicious log entries in /var/log/apache2/access.log or /var/log/nginx/access.log

• Behavioral IOCs:

  • Unexpected server-side requests to internal services (e.g., Redis, Elasticsearch, databases)
  • Increased latency or errors from internal services due to scanning

Detection Engineering

YARA Rule

rule CVE_2025_68030_SSRF_Frontis_Blocks {
    meta:
        description = "Detects SSRF exploitation attempts against Frontis Blocks plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-68030"
    strings:
        $url_pattern = /(http|https):\/\/(10\.\d{1,3}\.\d{1,3}\.\d{1,3}|172\.(1[6-9]|2[0-9]|3[0-1])\.\d{1,3}\.\d{1,3}|192\.168\.\d{1,3}\.\d{1,3}|169\.254\.\d{1,3}\.\d{1,3}|127\.\d{1,3}\.\d{1,3}\.\d{1,3}|0\.0\.0\.0)/
        $meta_pattern = "169.254.169.254"
        $plugin_path = "wp-content/plugins/frontis-blocks"
    condition:
        any of ($url_pattern, $meta_pattern) and $plugin_path
}

Sigma Rule

title: CVE-2025-68030 SSRF Exploitation via Frontis Blocks
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects SSRF attempts targeting internal IPs via Frontis Blocks plugin
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/wp-json/frontis-blocks/v1/fetch'
        cs-uri-query|contains: 'url=http://'
    filter:
        cs-uri-query|contains:
            - 'url=http://example.com'
            - 'url=http://cdn.example.com'
    condition: selection and not filter
falsepositives:
    - Legitimate use of external URLs (if any)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-68030 SSRF Exploitation - Frontis Blocks"; flow:to_server,established; content:"POST"; http_method; content:"/wp-json/frontis-blocks/v1/fetch"; http_uri; content:"url=http://"; http_client_body; pcre:"/url=http:\/\/(10\.\d{1,3}\.\d{1,3}\.\d{1,3}|172\.(1[6-9]|2[0-9]|3[0-1])\.\d{1,3}\.\d{1,3}|192\.168\.\d{1,3}\.\d{1,3}|169\.254\.\d{1,3}\.\d{1,3}|127\.\d{1,3}\.\d{1,3}\.\d{1,3}|0\.0\.0\.0)/"; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Since no official patch is available, the following mitigations are recommended:

1. Disable the plugin: Immediately deactivate and remove the Frontis Blocks plugin from all WordPress installations until a patch is released.
2. Web Application Firewall (WAF): Deploy WAF rules to block requests to /wp-json/frontis-blocks/v1/fetch with internal IP addresses in the url parameter.
3. Network Segmentation: Restrict outbound HTTP access from the WordPress server to only necessary external domains using a proxy or firewall.
4. Monitor Logs: Enable detailed logging for web server and application logs, and set up alerts for SSRF patterns.
5. Update: Monitor the WordPress plugin repository for updates and apply patches as soon as they become available.

Valters IT
Securing Digital Frontiers