A vulnerability has been discovered in the popular WordPress plugin, Themeisle Redirection for Contact Form 7, which allows an attacker to exploit misconfigured access control security levels. The affected versions are from n/a through 2.9.2. This vulnerability has been assigned the CVE identifier CVE-2023-39920.

In this long read, we'll dive into the details of CVE-2023-39920, including the code snippet responsible for the vulnerability, relevant links to original references, and specifics of the exploit. The language will be simple and in American English to make it easy to understand.

Description of Vulnerability

In Themeisle Redirection for Contact Form 7, a missing authorization vulnerability exists which could allow an attacker to exploit wrongly configured access control security levels. Essentially, this means that if access control on a vulnerable site is not set up correctly, an attacker could perform unauthorized actions that could lead to information disclosure, unwanted modifications, or even the deletion of data.

This vulnerability exists due to an absence of proper authorization checks in the plugin's code. Let's look at the code snippet responsible for the vulnerability to deepen our understanding of the issue.

Code Snippet

function wpcf7r_update_post() {
    global $post;
    $current_nonce = $_REQUEST['wpcf7r_nonce'];
    $wpcf7r_api_key = $_REQUEST['wpcf7r_api_key'];
    $post_id = $_REQUEST['postid'];

    if ( wp_verify_nonce( $current_nonce, 'wpcf7r_update_post' ) ) {
        $my_post = array(
          'ID'           => $post_id,
          'post_content' => $_REQUEST['shortcode']
        );

        // Update the post into the database
        wp_update_post( $my_post );
    }
}
add_action( 'wp', 'wpcf7r_update_post' );

As we see in the code snippet above, the wpcf7r_update_post() function is responsible for updating the post content. However, it fails to perform proper authorization checks to verify if the user has the necessary permissions to update the post.

To get a better understanding of this vulnerability and its exploitation, let's take a look at the original references that disclosed this issue.

Original References

1. Themeisle Redirection for Contact Form 7 Security Advisory
2. CVE-2023-39920
3. Plugin Vulnerabilities

Now, let's examine the details of this exploit and learn how it can be used by an attacker.

Exploit Details

To exploit this vulnerability, an attacker needs to send a specially crafted request to a vulnerable site. Here's an example of the request that needs to be sent:

POST /wp/ HTTP/1.1
Host: vulnerable-site.com
Content-Length: 194
Content-Type: application/x-www-form-urlencoded

wpcf7r_nonce=VALID_NONCE&wpcf7r_api_key=API_KEY&postid=POST_ID&shortcode=[attacker_controlled_content]

By sending such a request, an attacker can update the post content to include malicious content of their choice. Thus, they can modify the website's content, disclose sensitive information, or even delete data if the access control security levels are not correctly configured.

To protect your site from this vulnerability, it's important to update to the latest version of Themeisle Redirection for Contact Form 7. Additionally, ensuring proper access control configurations can also minimize the risk of exploitation.

Conclusion

CVE-2023-39920 is a missing authorization vulnerability in Themeisle Redirection for Contact Form 7 that could lead to exploiting incorrectly configured access control security levels. This issue affects versions from n/a through 2.9.2. It's essential to update your website to the latest version and ensure proper access control configurations to prevent exploitation.

Timeline

Published on: 12/13/2024 14:23:58 UTC