Executive Summary

A Cross-Site Request Forgery (CSRF) vulnerability has been identified in the Insert Headers And Footers plugin for WordPress, tracked as CVE-2025-2111. This vulnerability, rated as HIGH severity with a CVSS score of 7.5, affects all versions of the plugin up to and including 3.1.1. The root cause lies in the missing or insufficient nonce validation within the custom_plugin_set_option function. An attacker can exploit this by crafting a malicious request that, when triggered by a logged-in administrator, allows them to modify arbitrary WordPress options. This can lead to severe consequences, including elevating an attacker's privileges to administrator and gaining full control over the affected website. The vulnerability requires the WPBRIGADE_SDK__DEV_MODE constant to be set to true to be exploitable.

Vulnerability Snapshot

Technical Deep Dive

The core of this vulnerability resides in the custom_plugin_set_option function within the Insert Headers And Footers plugin. The absence of proper nonce validation allows an attacker to forge requests on behalf of an authenticated administrator. Let's break down how this works:

1. The Vulnerable Function: The custom_plugin_set_option function is responsible for updating plugin options. Ideally, this function should verify that any incoming request originated from a legitimate source within the WordPress admin panel.

2. Nonce Validation (or Lack Thereof): WordPress uses nonces (Number used Once) as a security token to prevent CSRF attacks. A nonce is a unique, randomly generated string that is embedded in a form or URL. When the form is submitted or the URL is accessed, the server verifies that the nonce is valid. In this case, the custom_plugin_set_option function lacks proper nonce validation or uses an easily bypassed implementation.

3. CSRF Attack Scenario:

   • An attacker crafts a malicious HTML page containing a form that submits data to the custom_plugin_set_option function. This form is designed to modify a critical setting, such as the default user role upon registration.
   • The attacker tricks a logged-in WordPress administrator into visiting this malicious page (e.g., through a phishing email).
   • When the administrator visits the page, the form is automatically submitted in the background, sending the forged request to the WordPress site.
   • Because the administrator is authenticated, the forged request is executed, and the targeted option is updated.

4. Exploitation Example: Privilege Escalation

   • The attacker can exploit this vulnerability to change the default_role option in WordPress to administrator.
   • The attacker then enables user registration on the WordPress site.
   • The attacker registers a new account.
   • The new account is automatically assigned the administrator role, granting the attacker full control over the WordPress site.

5. The Devil in the Details: WPBRIGADE_SDK__DEV_MODE The vulnerability is only exploitable when the WPBRIGADE_SDK__DEV_MODE constant is set to true. This likely means the vulnerable code path is only active in development mode, which should not be enabled in production environments. However, misconfigurations happen, making this vulnerability a potential threat.

A simplified example of a vulnerable code snippet (illustrative only, not the actual code):

<?php
// Vulnerable function (illustrative)
function custom_plugin_set_option() {
  if (isset($_POST['option_name']) && isset($_POST['option_value'])) {
    // Missing nonce validation!
    update_option($_POST['option_name'], $_POST['option_value']);
    echo "Option updated!";
  } else {
    echo "Invalid request.";
  }
}
?>

In contrast, a secure implementation would include nonce verification:

<?php
// Secure function (illustrative)
function custom_plugin_set_option() {
  if (isset($_POST['option_name']) && isset($_POST['option_value']) && check_admin_referer( 'my_plugin_action', 'my_plugin_nonce' )) {
    update_option($_POST['option_name'], $_POST['option_value']);
    echo "Option updated!";
  } else {
    echo "Invalid request or invalid nonce.";
  }
}
?>

The check_admin_referer() function is a WordPress built-in function that verifies the nonce.

Proof-of-Concept (POC) Insights

Potential POCs may be available via the provided references. These POCs likely demonstrate how to craft a malicious request that can be used to exploit the CSRF vulnerability. Given that the vulnerability allows arbitrary option updates, potential POCs may focus on elevating privileges, injecting malicious code into the site, or redirecting users to phishing sites.

Warning: POC code is intended for educational and research purposes only. Executing POC code can cause harm and may be illegal. Use extreme caution.

Threat Actor Activity

No known threat actor associations at this time. However, CSRF vulnerabilities are often exploited by opportunistic attackers and botnets. The ease of exploitation (once an administrator is tricked) makes this a valuable target for attackers seeking to compromise WordPress sites.

Impact Assessment

The exploitation of CVE-2025-2111 can have significant consequences:

• Confidentiality: An attacker with administrative access can view and exfiltrate sensitive data stored in the WordPress database, including user credentials, customer information, and proprietary content.
• Integrity: An attacker can modify website content, inject malicious code, deface the site, or redirect users to phishing pages. They could also modify plugin settings, potentially creating backdoors for persistent access.
• Availability: An attacker can disable the website, delete critical files, or overload the server, leading to denial-of-service conditions.

For organizations using AWS PaaS environments, the impact could extend to applications deployed on those platforms. A compromised WordPress site could be used as a springboard to attack other applications or services within the same AWS account.

Cloud Service Provider Implications

While there is no direct AWS impact identified, cloud service providers, especially those offering WordPress hosting or PaaS solutions, should be aware of this vulnerability. Here's a breakdown of potential implications:

• AWS-hosted Applications: If a customer's WordPress site hosted on AWS is compromised, it could potentially affect other applications and services within their AWS environment, especially if they share credentials or resources.
• Customer-Managed Components: The vulnerability exists within a WordPress plugin, which is typically a customer-managed component. Therefore, the responsibility for patching and mitigating the vulnerability lies with the customer.
• Multi-Tenant Environments: In multi-tenant environments, a compromised WordPress site could potentially impact other tenants if proper isolation mechanisms are not in place. Cloud providers should ensure robust isolation to prevent cross-tenant contamination.
• Data Residency/Compliance: Data breaches resulting from the exploitation of this vulnerability could have serious data residency and compliance implications, especially if sensitive data is stored in the WordPress database.

Mitigation and Remediation

The primary mitigation strategy is to update the Insert Headers And Footers plugin to the latest version. Vendor advisories should be consulted for specific patch information and workarounds.

In addition to patching, consider the following:

• Disable WPBRIGADE_SDK__DEV_MODE: Ensure that the WPBRIGADE_SDK__DEV_MODE constant is set to false in production environments. This will prevent the vulnerable code path from being executed.
• Web Application Firewall (WAF): Implement WAF rules to detect and block malicious requests targeting the custom_plugin_set_option function.
• Principle of Least Privilege: Limit the number of users with administrative privileges on the WordPress site.
• User Awareness Training: Educate administrators about the risks of CSRF attacks and the importance of being cautious when clicking on links or opening attachments from unknown sources.
• Regular Security Audits: Conduct regular security audits of WordPress sites and plugins to identify and address vulnerabilities.

References

• WordPress Plugin Source Code - Line 63
• WordPress Plugin Source Code - Line 69
• WordPress Plugin Changeset 3276361
• Wordfence Threat Intel Report
• OWASP CSRF Prevention Cheat Sheet

Conclusion

CVE-2025-2111 highlights the importance of proper input validation and nonce implementation in web applications. The potential for privilege escalation and complete site takeover makes this a serious vulnerability that should be addressed promptly. For organizations using cloud service providers, especially those with workloads on AWS PaaS offerings, it's crucial to ensure that WordPress sites are properly secured and regularly updated to mitigate the risk of exploitation. Staying informed about vulnerabilities and implementing robust security practices are essential for protecting your online assets. Consider exploring resources like the OWASP CSRF Prevention Cheat Sheet for further guidance on preventing CSRF attacks.