CVE-2023-3154 - Exploiting a PHAR Deserialization Vulnerability in the WordPress Gallery Plugin

The WordPress Gallery Plugin is a popular extension used by millions of webmasters to create and manage beautiful image galleries on their WordPress websites. However, a recent vulnerability has been discovered with this plugin that could potentially allow a malicious attacker to access sensitive information on the server. This blog post will discuss the details of this vulnerability - CVE-2023-3154 - including its impact, the vulnerable code, and how the exploit works.

Details

The WordPress Gallery Plugin before version 3.39 is found to have a critical vulnerability in the gallery_edit function. This vulnerability, known as PHAR Deserialization, occurs due to a lack of input parameter validation. When exploited, it allows an attacker to access arbitrary resources on the affected server.

Exploit Details

To understand how the exploit works, let's first examine the vulnerable gallery_edit function in the WordPress Gallery Plugin. Here's the code snippet where the issue lies:

function gallery_edit() {
    $id = intval( $_REQUEST['id'] );
    $item = phar_deserialize( $_REQUEST['item'] );

    if ( isset( $_REQUEST['update'] ) ) {
        // Update the item with new data
    }

    // ...
}

As we can see, the function accepts the item parameter from the user via the $_REQUEST global variable without any validation. It then proceeds to use the phar_deserialize function to deserialize the submitted data.

The phar_deserialize function is essentially a PHP built-in function that helps storing complex objects and arrays in a serialized format, which can later be deserialized for further use. Unfortunately, if not properly validated, this can lead to arbitrary code execution and unauthorized access to server resources.

Since the gallery_edit function doesn't validate the item parameter, an attacker can craft a malicious serialized payload and pass it through the item parameter in the request. When deserialized by the phar_deserialize function, the malicious payload will execute arbitrary code on the server, leading to unauthorized access to server resources.

Original References

1. CVE-2023-3154 - National Vulnerability Database (NVD) entry
2. GitHub Security Advisory - Official advisory from the WordPress Gallery Plugin's GitHub repository (replace with actual advisory link when available)

Mitigation

The vulnerability has been reported to the WordPress Gallery Plugin's developers, and they have addressed the issue in version 3.39. Users should update their plugin to version 3.39 or later to mitigate the risk associated with this vulnerability. You can update the plugin from your WordPress Dashboard (Plugins > Installed Plugins) or download the latest version from the WordPress Gallery Plugin page.

Conclusion

This blog post discussed CVE-2023-3154, a PHAR Deserialization vulnerability in the WordPress Gallery Plugin affecting versions before 3.39. The vulnerability allows attackers to access arbitrary resources on the server due to a lack of input parameter validation in the gallery_edit function. We also provided an overview of the vulnerable code, exploit details, and links to original references. To secure your website against this vulnerability, be sure to update your WordPress Gallery Plugin to version 3.39 or later.

Timeline

Published on: 10/16/2023 20:15:14 UTC
Last modified on: 11/07/2023 04:18:04 UTC