Recently, a vulnerability has been discovered affecting the popular WordPress plugin, Backup and Staging by WP Time Capsule. This vulnerability is identified as CVE-2024-8856 and allows unauthenticated attackers to upload arbitrary files to the server running the vulnerable WordPress site. This opens the door to potential remote code execution, putting the affected site, its data and users at significant risk.
Affected Plugin and Versions
The vulnerability affects all versions of the Backup and Staging by WP Time Capsule plugin up to and including version 1.22.21. WP Time Capsule is a popular WordPress plugin used for creating backups and staging environments for millions of websites.
Details of the Vulnerability
The vulnerability is caused due to the lack of proper file type validation in the UploadHandler.php file and the absence of prevention mechanisms against direct file access. This makes it possible for unauthenticated attackers to upload files with malicious content onto the server where the affected WordPress site is hosted.
Here's a snippet from the vulnerable code in the UploadHandler.php file
public function post()
{
$uploadedFile = $this->$file;
//...
if ( $uploadedFile->name )
{
$file_path = $this->options['upload_dir'].$uploadedFile->name;
if (!is_file( $file_path )) {
$uploadedFile['uploaded'] = 1;
}
}
}
In the above code, no validation checks have been applied to ensure that only certain file types can be uploaded. This allows attackers to upload malicious files such as PHP scripts, which can potentially be executed on the server.
Exploit Details
To exploit this vulnerability, an attacker would craft a malicious HTTP POST request containing a file with malicious content. The request can be sent to the server where the affected WordPress site is hosted through a REST API endpoint provided by the plugin. As there is no authentication required for this request, an unauthenticated attacker will be able to successfully upload the file. Once the file is uploaded, the attacker can access it through the site's URL and execute it by invoking the URL in the browser.
Example of a malicious HTTP POST request to exploit the vulnerability
POST /wp-json/wp-time-capsule/v1/files HTTP/1.1
Host: example.com
Content-Length: 12345
Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryvZMC5C6B35gYxJQ9
------WebKitFormBoundaryvZMC5C6B35gYxJQ9
Content-Disposition: form-data; name="uploaded-file"; filename="malicious-file.php"
Content-Type: application/octet-stream
[Malicious file content]
------WebKitFormBoundaryvZMC5C6B35gYxJQ9--
Recommendations & Mitigation
To protect your WordPress site from this vulnerability, it is crucial to update the Backup and Staging by WP Time Capsule plugin to the latest version. In addition, ensure that your WordPress installation, themes, and other plugins are up to date to prevent possible exploitation of any other vulnerabilities.
Additionally, it is a good practice to restrict access to your /wp-content/uploads/ directory using a .htaccess file. This prevents users from accessing or executing any potentially malicious files that may have been inadvertently uploaded.
For more information on this vulnerability and its impact, please refer to the following sources
1. CVE-2024-8856 - WP Time Capsule Arbitrary File Upload Vulnerability
2. WP Time Capsule Plugin Security Advisory
Conclusion
In summary, CVE-2024-8856 is a severe vulnerability affecting the Backup and Staging by WP Time Capsule plugin for WordPress, which allows unauthenticated attackers to upload arbitrary files and potentially execute them on the server. Users should update the plugin urgently to the latest version to mitigate the risk of exploitation.
Timeline
Published on: 11/16/2024 05:15:13 UTC
Last modified on: 11/21/2024 16:15:27 UTC