CVE-2023-28782 - Exploiting Deserialization of Untrusted Data Vulnerability in Rocketgenius Inc. Gravity Forms (Versions n/a - 2.7.3)

In this long read article, we'll be discussing a critical vulnerability that has been discovered in the popular WordPress plugin, Gravity Forms, created by Rocketgenius Inc. This vulnerability, assigned as CVE-2023-28782, is a Deserialization of Untrusted Data vulnerability and can be exploited by an attacker to gain unauthorized access, execute arbitrary code, and read sensitive information from a website that uses the affected version of Gravity Forms.

Gravity Forms is a popular form creation and management plugin for WordPress websites, used by millions of sites to collect information from users and manage their input data. This vulnerability affects versions of Gravity Forms from n/a through 2.7.3.

In this post, you'll find a detailed explanation of the vulnerability, a code snippet illustrating the problem, links to original references, and exploit details, including potential attack scenarios. To fully understand this vulnerability, we recommend that you are familiar with WordPress plugin development, PHP programming, and object serialization/deserialization concepts.

Vulnerability Details

The Deserialization of Untrusted Data vulnerability in Gravity Forms is caused by the unsafe handling of serialized PHP objects when processing input data. A serialized PHP object is a string representation of an object that can be stored and later recreated using PHP's unserialize() function.

Here is a simplified code snippet illustrating the vulnerability (note that this is not the actual plugin's code, but a representation for demonstration purposes):

<?php
// Class definition for a Gravity Forms object
class GravityForm {
    public $form_data;
    
    public function set_form_data($data) {
        $this->form_data = $data;
    }
    
    public function execute_code() {
        // Arbitrary code execution logic
    }
}

// An attacker can craft a malicious serialized string
$malicious_serialized_data = 'a serialized string containing manipulative object data';

// The vulnerable plugin processes the input data
$unsafe_object = unserialize($malicious_serialized_data);

// The unsafe object is an instance of the GravityForm class
$unsafe_object->execute_code(); // An attacker's code might be executed here
?>

In the above code snippet, an attacker could craft a malicious serialized string containing manipulative object data and pass it to the unserialize() function, which might lead to unauthorized access, arbitrary code execution, and sensitive information disclosure.

Exploit Scenarios

The primary attack scenario for exploiting this vulnerability would involve an attacker sending a crafted request to a vulnerable WordPress website, containing malicious serialized PHP object data. The attacker would target the vulnerable Gravity Forms plugin code responsible for processing user input, such as form submissions.

By manipulating the object properties in the malicious serialized data, an attacker could overwrite sensitive variables or execute arbitrary code on the website, potentially leading to a full system compromise.

Here are links to the original references for more information about this vulnerability

1. CVE-2023-28782 - NVD
2. Exploit Database - CVE-2023-28782
3. Official Gravity Forms Security Advisory

Mitigation

To protect your WordPress site from this vulnerability, it is strongly recommended that you update the Gravity Forms plugin to at least version 2.7.4, which has been patched to address this issue. You should also follow WordPress security best practices, such as keeping your plugins and themes up-to-date, using strong and unique passwords, and limiting user privileges.

Conclusion

In this article, we've explored the CVE-2023-28782 vulnerability - a Deserialization of Untrusted Data vulnerability in the popular WordPress plugin, Gravity Forms, affecting versions from n/a through 2.7.3. By understanding this vulnerability and following the mitigation steps provided, you can help protect your WordPress websites from potential attacks and keep your users' data safe and secure.

Timeline

Published on: 12/20/2023 15:15:07 UTC