Exponent CMS 2.6.0 patch2 - Insecure file upload (RCE Upload new extension)
Reported by Oscar | January 24th, 2022 @ 05:32 PM
Bug description
Exponent CMS 2.6.0 patch2 allows an
authenticated admin user to upload a malicious extension in the
format of a zip file with a php file inside it.
After uploaded it, the php file will be placed at
themes/simpletheme/{rce}.php
from where can be
accessed to execute commands.
CVSSv3 Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
CVSSv3 Base Score: 9.1
Steps to reproduce
- Click on the Exponent logo located on the upper left
corner.
- Go to 'Super-Admin Tools' > 'Extensions' > 'Install
Extension'.
- Click on 'Upload Extension'.
- Create a malicious PHP file with the following PoC.
<?php echo system($_GET['cmd']); ?>
- Zip the php file.
- Upload the zip file.
- Click on 'Upload Extension'
- Next, click on 'Continue with Installation'.
- Go to
http://127.0.0.1/exponentcms/themes/simpletheme/{rce}.php
in order to execute commands
Attached below are the links to the advisory and our responsible disclosure policy.
System Information
- Version: Exponent CMS 2.6.0 patch2.
- Operating System: Linux.
- Web Server: Apache
- PHP Version: 7.4
- Database and version: Mysql
Comments and changes to this ticket
-
dleffler February 12th, 2022 @ 09:40 PM
- Assigned user changed from expNinja to dleffler
I'm not sure I follow your logic. A Super-Admin by definition is granted permission to pretty well take down the site any number of ways?
-
Oscar February 17th, 2022 @ 04:12 PM
Any functionality that allows functions/actions other than those planned are cases of abuse, regardless of the context (the impact is given by the rating). Abuse cases are usually vulnerabilities that need to be fixed.
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